2023 TOP 100 GOOD PRACTICE STORY
タイトル (Title)「3 年に⼀度の祖⾕のかずら橋架け替え」
Vine Architects Preserving the Iya Vine Bridge Every 3 Years
申請地域 (Application Area)

三好市
Miyoshi City
①ストーリーの概要（Summary）

⽇本三奇橋の⼀つとして数えられ、国指定重要有形⺠俗⽂化財に指定されている「祖⾕のかずら橋」は、四国・徳島・三好市の“秘境”祖⾕に架かるシラクチカズラでつくられたつり橋で、⻑さ 45ｍ・幅 2ｍ・⽔⾯上 14ｍ、昔は深⼭渓⾕地帯において対岸に渡る唯⼀の交通⼿段だったものが、今では、年間約 35 万⼈の観光客が訪れ、渡橋体験できる、三好市の重要な観光資源となっている。
かずら橋は、⽼朽化のためと、その架け替え技術の伝承のために、３年に⼀度、地元「かずら橋保勝会」によって架け替え作業が⾏われている。今も⾃然にある材料（シラクチカズラ）を使って昔ながらのやり⽅で、ほぼ⼿作業でこれだけ⼤きな橋を作っている。材料となるシラクチカズラは、祖⾕の⼭に⾃⽣していたものだが、近年は、かずら橋の材料となるだけの量が⼿に⼊りにくくなってしまった。
そこで、森林管理署と、祖⾕のかずら橋架け替え資材確保実⾏委員会を設置、「⽊の⽂化を⽀える森づくり協定」「祖⾕の蔓橋シラクチカズラ資材確保協定」を締結。架け替え資材確保のため、⾼知県にある国有林から調達すると共に、地元祖⾕では、⼩中学⽣と⼀緒に環境学習として、シラクチカズラの苗を育て、東祖⾕の国有林に植樹し、資材の地元調達を⽬指している。
伝統的資材の確保と、架け替え技術の伝承による、3 年に⼀度の架け替えを継続することで、コロナ過の影響を受け⼀時激減することとなったが、地域の⾃然⽂化体験を好む外国⼈来訪者を含め渡橋者数は年間 35 万⼈前後を推移している。地元⾃然林への苗の植樹も 200 本の活着が確認され、かずら橋の架け替えには樹齢 20 年は必要と⾔われるシラクチカズラの⽣育、資材の地元調達にも⼀定の⽬途が⽴つこととなった。
The Iya Vine Bridge or Iya Kazura Bridge, one of the three strangest bridges in Japan anddesignated as a National Important Tangible Folk Cultural Property, is a suspension
bridge made of Japanese holly vine, 45m long, 2m wide, and 14m above the surface of thewater, which used to be the only means of transportation across the deep mountain valley
to the other side of the river, but now it is an important tourist resource in Miyoshi City,attracting about 350,000 tourists a year.
The Iya Kazura Bridge is replaced every three years by the local "Iya Kazura Bridge
Preservation Association" due to its aging and to pass on the replacement techniques.
The bridge is still being built in the traditional way, using natural materials and almost allof the work is done by hand. The material used to make the bridge is the Shirakuchikazura, which used to grow wild in the mountains of Iya, but in recent years it has become
difficult to obtain enough of the material to make the bridge.
Therefore, a committee was set up with the Forest Service to secure materials for thereplacement of the Iya Kazura Bridge, and an "Agreement on Creating a Forest thatSupports Wood Culture" and an "Agreement on Securing Materials for the Iya Vine
Bridge" were concluded. In addition to procuring materials to replace the bridge from thenational forest in Kochi Prefecture, the committee is also working with local elementaryand junior high school students to grow Shirakuchi-kazura seedlings and plant them in
the national forest in the East Iya Valley as part of their environmental education
program, aiming to procure materials locally.
By securing traditional materials and passing on the bridge-building techniques, thenumber of visitors -- including foreign visitors who prefer to experience the local natureand culture --has remained around 350,000 per year, although the number of bridgecrossings has temporarily declined sharply due to the COVID-19 pandemic. The plantingof 200 seedlings in the local natural forest has been confirmed, and there is now a certain
prospect for the growth of the Shirakuchi-kazura, which is said to be 20 years and will beneeded to replace the Iya Kazura Bridge, as well as for the procurement of materials
locally.
②観光地の説明（DESTINATION DESCRIPTION）

ゆらゆらと揺れる橋を年間約 35 万⼈の観光客が渡る、四国の秘境、徳島県三好市⻄祖⾕村にある“祖⾕のかずら橋”、⽇本三奇橋の⼀つとして数えられていて、重要有形⺠俗⽂化財に指定されている。⻑さ約 45ｍ、幅約２ｍ、⽔⾯からの⾼さ約 14ｍに架かる、重さ約６トンにもなる⾃⽣のシラクチカズラ（サルナシ） を編み上げて作られている。
かずら橋は、その昔、祖⾕に逃れた平家の落⼈が、源⽒が攻め寄せた場合に直ちに橋を切り落として、その侵⼊を防ぐために架けたという説や、弘法⼤師が祖⾕に⼊⼭したとき、浮橋が⼤⽔で流され困っている村⼈をご覧になり、丈夫で腐りにくいシラクチカズラを使った吊り橋の架け⽅を教えて頂いたのだという説など、諸説残っている。
深⼭渓⾕に住む⼈々にとって、⼤⽔でも流されない頑丈なかずら橋は、なくてはならない⽣活道であった。かずら橋は厳しい祖⾕の⾵⼟と⼭暮らしの知恵の結晶である。
明治の時代には東⻄祖⾕地域に 13 橋が架かっていたとされる“かずら橋”も、⼤正時代には全て針⾦吊橋にかわり、その役⽬を終えていた。当時の隣町の池⽥町⻑の「観光資源としてかずら橋を再興しよう」との声掛けにより、⻄祖⾕善徳⻘年団、校下⻘年団の⻘年たち（後の「かずら橋保勝会」）が現在の場所（⻄祖⾕⼭村善徳）に、伝統的な資材、⼯法によるかずら橋を再興したのです。昭和 3 年 3 ⽉のことでした。そこには両岸に⽀点となる⼤⽊があり、近くにはシラクチカズラの加⼯に必要な滝つぼがあり、その他伝統的な架け⽅に適し、集落間の⽣活道としても適した場所でした。その後、昭和14 年よりは、3 か年ごとに架け替えを実施、観光資源として来訪者を迎えるにあたり、伝統的なかずら橋の製作⼯程を重視し、踏まえながら、安全性と橋の強度や耐久性についても検討を加え、観光資源として渡橋体験について、以降のかずら橋の維持修繕、架け替え経費の財源を⽬的に、昭和 41 年からは渡橋料 50 円を徴収、有料で提供する事となるのです。
現在は、四国の“秘境”祖⾕の⽣活と歴史⽂化を体験できる、観光資源として、その⽼朽化と、架け替え技術の継承のため、３年に⼀度、かずら橋保勝会によって、架け替えが⾏われています。
The Iya Kazura Bridge in Nishi-Iya Village, Miyoshi City, Tokushima Prefecture, isone of the three strangest bridges in Japan, and is designated as an Important Tangible
Folk Cultural Property. The bridge is about 45 meters long, 2 meters wide, and 14 meters
high above the water, and is made of woven native Japanese pines that can weigh up to 6tons.
Kazura-bashi Bridge is said to have been built in the old days by Heike fugitives whofled to Iya in order to prevent the invasion of the Genji by cutting off the bridge
immediately. It is also said that when Kobo Daishi entered Iya, he saw villagers in trouble
because their floating bridge had been washed away by heavy water. So he taught them
how to build a suspension bridge using the strong and rot-resistant Shirakuchi-kazura(Salix vine).
For the people living in the deep mountain valley, the Iya Kazura Bridge, which isstrong enough to withstand heavy water, was an indispensable way of life. The Iya Kazura
Bridge is the fruit of the harsh climate of Iya and the wisdom of mountain life.
In the Meiji era (1868-1912), it is said that there were 13 such bridges in the East andWest Iya regions, but by the Taisho era (1912-1926), they had all been replaced by wiresuspension bridges, and their role had come to an end. The mayor of Ikeda, a neighboring
town at the time, called for the revival of the bridge as a tourist resource, and the youthsof the Nishi-Iya Zentoku and Koshita youth groups (later the Iya Kazura Bridge
Preservation Association) rebuilt the bridge using traditional materials and construction
methods at its current location (Zentoku, Nishi-Iya Mountain Village). This was in March
1928. There were large trees on both banks of the bridge that served as fulcrums, andnearby was a waterfall basin necessary for processing shirakuchi-kazura, making it asuitable location for the traditional method of building the bridge, as well as a suitableroad for living between the villages. Since 1939, the bridge has been rebuilt every threeyears, and in order to welcome visitors as a tourist resource, we have been focusing on thetraditional Iya Kazura Bridge production process, while also considering the safety,
strength, and durability of the bridge. We have been planning a bridge crossing
experience as a tourist resource, in order to fund the maintenance, repair, and rebuilding

costs of the bridge. In 1966, a fee of 50 yen was charged to cross the bridge to raise funds
for future maintenance, repair, and replacement of the bridge.
Currently, the bridge is being replaced once every three years by the Iya Kazura Bridge
Preservation Association to replace the aging bridge and pass on the replacement
technology as a tourist resource that allows visitors to experience the life, history, andculture of Iya, the "unexplored region" of Shikoku.
③直⾯した課題（ISSUES FACED）

国指定重要有形⺠俗⽂化財「祖⾕の蔓橋」は、シラクチカズラで架けられており、⼤量の植物性資材を必要とする。
観光資源として、歴史的建造物を後世に伝えていくためには、定期的な修理が必要であり、重要⽂化財の保存修理においては、その架け替え技術の伝承、担い⼿の確保と共に、従来と同品種、同品質の資材を確保することが必要である。しかし近年は、その修理架け替え⽤資材の安定的な確保が困難な状況となっている。
こうした事態により、従来の地元産材料だけでなく、県外からの確保も必要となり、コスト⾯等で⼤きな負担が発⽣し課題となっている。
The Iya Kazura Bridge, a nationally designated Important Tangible Folk Cultural
Property, is constructed of shirakuchi-kazura, which requires a large amount of plantmaterials.
In order to preserve and repair important cultural properties, it is necessary to securematerials of the same variety and quality as in the past, as well as to hand down thereplacement techniques and secure the people who will be responsible for the work. In
recent years, however, it has become difficult to secure stable supplies of replacement
materials for such repairs.
This situation has created a significant cost burden, requiring not only locally produced
materials, but also materials from outside the prefecture.
④課題解決の対策⽅法、ステップ、ツール（METHODS, STEPS AND TOOLSAPPLIED）「祖⾕のかずら橋」の資材確保は、以下のステップで取り組まれました。
2008 年
徳島県三好市と四国森林管理局徳島森林管理署は、祖⾕のかずら橋架け替え資材確保実⾏委員会を設置、市内で調達できなくなったシラクチカズラを、⾼知県の国有林から調達、森林の整備の上で、⽊の⽣育の邪魔になっているカズラを、かずら橋の架け替え資材として無償で提供してもらい、かずら橋保勝会が調達することになりました。
あわせて、地元における資源確保に向けて、「⽊の⽂化を⽀える森づくり協定」を締

結、地域の⼦供たちとともにシラクチカズラの苗⽊を育て、三好市東祖⾕の国有林に植樹する取り組みを始めました。
2017 年
苗⽊は育ち⾃然林に植樹するも、その⽣育環境とシカの⾷害に負け活着が進まないことから、⾹川⼤学農学部と徳島森林管理署、三好市で「祖⾕の蔓橋シラクチカズラ資材確保協定」を締結、マタタビ属植物の増殖・育成の権威である⾹川⼤学⽚岡教授に指導を受けることになりました。
2019 年〜2022 年
苗⽊を育成するには挿し⽊から育てて約 5 年間、⼩中学⽣と共に東祖⾕国有林に植樹。
⾹川⼤学⽚岡教授の指導のもと、シラクチカズラを植栽する箇所の条件（⽔はけ、陽光）に配慮、ニホンジカの⾷害を避けるためにシカネットを整備するなど対策をし、⾒事に活着し、順調に成⻑している。
これまで 15 年間で約 1500 本植樹し、約 200 本の活着が確認されている。
The following steps were taken to secure materials for the Iya Kazura Bridge:
In 2008
Miyoshi City, Tokushima Prefecture, and the Tokushima Forest Office of the Shikoku
Regional Forest Office set up an executive committee to secure materials to replace theIya Kazura Bridge, and asked the Iya Kazura Bridge Conservation Association to provide
free of charge the Shirakuchi-kazura, which was no longer available in the city, from thenational forest in Kochi Prefecture. The Kazura Bridge Preservation Association willprocure these trees.
In addition, to secure local resources, we concluded a "Forestation Agreement to Support
the Culture of Trees" and began working with local children to grow Shirakuchi-kazura
saplings and plant them in the national forest in Higashi Iya, Miyoshi City.
In 2017
The saplings grew and were planted in a natural forest, but due to their growthenvironment and the fact that they were not thriving due to feeding damage caused bydeer, the Faculty of Agriculture of Kagawa University, Tokushima Forest Office, andMiyoshi City concluded an "Agreement on Securing Iya Kazura Bridge Shirakuchi-kazura
Materials" and received guidance from Professor Kataoka of Kagawa University, anauthority on the propagation and cultivation of plants in the genus Matatabi.
2019-2022
To cultivate the saplings, they will be grown from cuttings and planted in the East Iya

National Forest for about 5 years together with elementary and junior high school
students.
Under the guidance of Professor Kataoka of Kagawa University, they took measures suchas taking into consideration the conditions (drainage, sunlight) of the area where theShirakuchi-kazura were planted and maintaining deer nets to prevent feeding damage byJapanese deer, and the trees have successfully taken root and are growing well.
Over the past 15 years, approximately 1,500 trees have been planted, and approximately
200 trees have been confirmed to be thriving.
⑤成功の主要因（KEY FACTORS FOR SUCCESS）

祖⾕のかずら橋等の架け替え資材としてシラクチカズラを育成していくには、概ね 20年程度の時間を必要とする。また、育成過程において多くの課題や問題点もある。
このため、これらの課題や問題点を解決し、将来にわたって架け替え資材であるシラクチカズラを確実かつ安定的に供給(確保)していくため、マタタビ属植物の増殖・育成の権威である⾹川⼤学農学部から技術的⽀援を得て、シラクチカズラの挿し⽊の⽅法、育苗過程での⽇照・⽔管理、林内への植付け後の管理などの指導を受けながら、シラクチカズラの育成に取り組んでいる。
植栽は、地域の⼦供たちに参加してもらうことで、⽊育と、環境学習、⽊の⽂化継承に繋がっている。
また、シラクチカズラ（別名：さるなし）の実を活⽤した商品化についても取り組むこととし、耕作放棄地での栽培に向けて農業従事者を募集、三好市さるなし協議会として、苗⽊を配り、さるなしの実の栽培を実証。「全国さるなし・こくわサミット協議会」でも活動し、実の活⽤を通じた地域振興にも取り組んでいる。
It takes about 20 years to cultivate Shirakuchi-kazura as a material for replacing theIya Kazura Bridge and other bridges. In addition, there are many issues and problems in
the cultivation process.
Therefore, in order to solve these problems and issues and to ensure a reliable and stablesupply of shirakuchi-kazura as a replacement material in the future, we obtained technicalsupport from the Faculty of Agriculture, Kagawa University, an authority on propagationand cultivation of matatabi plants, The project is working to cultivate shirakuchi-kazura
with guidance on how to take cuttings, how to manage sunlight and water during theseedling growth process, and how to manage the plants after planting in the forest.
By having local children participate in the planting, the project is linked to tree education,environmental education, and the passing on of tree culture.

The Miyoshi City Sarukuchi Kazura (also known as "sarunashi") Council has also decided
to commercialize the fruit of the sarunashi, and has recruited farmers to cultivate saplings
on abandoned farmland. The Miyoshi City Sarunashi Council is also active in the"National Sarunashi/Kokuwa Summit Council" and is working to promote regional
development through the use of saplings.

⑥得られた知⾒（LESSONS LEARNED）•

架け替え作業の継続
・••架け替え資材の確保
・

⾼知県の国有林から調達

・

市内国有林への植栽

シラクチカズラの⽣育に良い条件シカネットの整備

架け替え作業の時期
・•

かずら橋保勝会による架け替え技術の継承

閑散期である冬季に⾏うことで、架け替え作業も観光資源にプロジェクトの主な効果
・

観光資源の安定的な供給

架け替え資材確保・時間の短縮・安全性の確保

・

地域の⼦供たちの苗づくり、⾃然林への植栽、環境学習、⽊育

・

シラクチカズラ（さるなし）の実の⼆次製品開発（ジュース・ワイン等）の可
能性•

他の市施策への波及
・「ウッドスタート宣⾔」（2019.2.16）地産地消の⽊製玩具を誕⽣祝い品として贈る⽊育事業•・

三好市森づくり条例（2019.6）

・

三好市森づくり基本計画「千年のかくれんぼ」の森構想（2020.3）

このプロジェクトの成功は、主に以下のステークホルダーに利益をもたらしたと考えます・

かずら橋の修繕・架け替え作業を担い、技術を継承する“かずら橋保証会”の⼈材育成と担い⼿の確保

・

観光客数が回復していくことによる、市内周辺観光関連事業者の利⽤客増加

・

地域の⼦供たちによる植栽「⽊の⽂化」継承

・・シラクチカズラ（サルナシ）の実の活⽤による耕作放棄地の解消、農業従事

者の⽣産意欲の向上- Continuation of replacement work・ Passing on replacement techniques by the Iya Kazura Bridge Conservation Society- Securing replacement materials
・ Procurement from national forests in Kochi Prefecture
・ Planting in national forests in the city Good conditions for the growth of Shirakuchikazura Deer nets
- Time of replacement work
・ The replacement work will be carried out during the off-season of winter, making thereplacement work a tourism resource.
- Main benefits of the project・ Stable supply of tourism resources, shortening of time and safety of replanting work,
securing of materials for replanting
・ Seedling production by local children, planting in natural forests, environmental
education, and tree education
・ Potential in developing secondary products (juice, wine, etc.) from the fruit of theshirakuchi-kazura (sarunashi) plant- Spread to other city policies
・ Declaration of "Wood Start" (February 16, 2019) Wood education project to give
locally produced and consumed wooden toys as birthday gifts
・ Miyoshi City forestation ordinance (2019.6)
・ Miyoshi City Basic Plan for Forest Development "Thousand Year Hide and Seek"
Forest Concept (2021.3)- We believe that the success of this project has mainly benefited the following
stakeholders:・ Human resource development and the securing of personnel for the "Iya Kazura
Bridge Guarantee Association," which is responsible for the repair and replacement of thebridge and for passing on the skills.
・ Increase in the number of visitors to the city and its surrounding tourism-related
businesses due to the recovery in the number of tourists.
・ Inherit "tree culture" by planting trees by local children
・ Elimination of abandoned farmland and increase in motivation of farmers to produce
by utilizing the fruit of the Japanese honeysuckle.
⑦成果と実績（RESULTS AND ACHIEVEMENTS）

・伝統的資材の確保により、⽂化財・観光資源としての“祖⾕のかずら橋”の保存、活⽤が継続できた。
・有料で渡橋体験を提供する事で、⽂化施設を観光資源として、保存、管理、維持修繕、活⽤することができた。
・シラクチカズラをこれまで 15 年間で 1500 本植樹したがあまり活着しなかったが、三者協定により、⾹川⼤学の⽚岡先⽣からアドバイスをいただいたおかげで、200 本の活着に成功している。
・かずら橋など地域の⾃然や歴史⽂化が外国⼈に関⼼を持たれ、年々インバウンド客が増加している。
・By securing traditional materials, we were able to continue the preservation and usageof the Iya Kazura Bridge as a cultural asset and tourist resource.
・By offering the experience of crossing the bridge for a fee, we were able to preserve,
manage, maintain, repair, and utilize the cultural facility as a tourism resource.
・The "Shirakuchi-kazura" (white cedar) planted 1,500 trees over the past 15 years, but
the trees did not grow well.
However, thanks to advice from Dr. Kataoka of Kagawa University through a tripartite
agreement, 200 trees have been successfully planted.
・The number of inbound visitors has been increasing year by year as they are interested
in the nature and historical culture of the area, such as the Iya Kazura Bridge.

⑧他の観光地のためのヒント （TIPS FOR OTHER DESTINATIONS）〇市・国・学による協定で地域の宝を守る〇地域の⽂化を継承するため、地域の⼦供たちに参画してもらう〇当該事業だけでなく幅広い⽬で事業を⾏う・他施策への波及（さるなしの実の活⽤、耕作放棄地の再⽣、森林整備、⾃然林への転換、こくわサミットへの参加、⽊育事業の展開など）〇 Agreements by the city, state, and academia to protect local treasures〇 Invite local children to participate in the inheritance of local culture〇 Implement projects with a broad perspective, not only the project in question, andspread it to other policies(Utilization of sarunashi nuts, rehabilitation of abandoned farmland, forest
maintenance, conversion to natural forests,
Participation in the "Kokuwa Summit," development of tree-education programs, etc.)⑨表彰・追加資料 （RECOGNITIONS AND ADDITIONAL REFERENCESATIONS）

三好市公式観光サイト「祖⾕のかずら橋」

https://miyoshi-tourism.jp/spot/iyanokazurabashi/
⽂化庁

国指定⽂化財等データベース

蔓橋の製作⼯程https://kunishitei.bunka.go.jp/heritage/detail/312/500
国⼟交通省 ⼿づくり郷⼟賞 受賞
https://www.mlit.go.jp/sogoseisaku/region/tedukuri/list/pref/list_36tokushima.html
市報みよし

特集「かずら橋を次世代へ」

https://www.miyoshi.itokushima.jp/fs/9/1/2/1/8/_/____.pdf&sa=U&ved=2ahUKEwiki96t3dD_AhUmlYBHRcAD8gQFnoECAAQAg&usg=AOvVaw3xXadSafVsi_99EmjuLAzI
四国森林管理局

シラクチカズラの資源確保に向けたこれまでの取組について

https://www.rinya.maff.go.jp/shikoku/tokusima/shirakutikazura.html
かずら橋の作り⽅や祖⾕の暮らしなどを紹介した「祖⾕のかずら橋ストーリー館」
https://www.miyoshi.itokushima.jp/fs/9/1/1/6/0/_/28_____.pdf&sa=U&ved=2ahUKEwiki96t3dD_AhUmlYBHRcAD8gQFnoECAYQAg&usg=AOvVaw3Rbx3F8IOifDyiQRzav1kj
Miyoshi City Official Tourism Site "Kazura Bridge in Iya"
https://miyoshi-tourism.jp/spot/iyanokazurabashi/
Agency for Cultural Affairs Database of National Designated Cultural Properties, etc.
Production process of the vine bridge
https://kunishitei.bunka.go.jp/heritage/detail/312/500
Ministry of Land, Infrastructure, Transport and Tourism
https://www.mlit.go.jp/sogoseisaku/region/tedukuri/list/pref/list_36tokushima.html
City newsletter Miyoshi, special feature "Passing on the Kazura Bridge to the Next
Generation" (Japanese only)
https://www.miyoshi.itokushima.jp/fs/9/1/2/1/8/_/____.pdf&sa=U&ved=2ahUKEwiki96t3dD_AhUmlYBHRcAD8gQFnoECAAQAg&usg=AOvVaw3 xXadSafVsi_99EmjuLAzI
Shikoku Regional Forest Office, Shikoku District Forest Office, Shikoku District Forest
Office, Shikoku District Forest Office, Shikoku District Forest Office, Shikoku District
Forest Officehttps://www.rinya.maff.go.jp/shikoku/tokusima/shirakutikazura.html
Iya Kazura Bridge Story Hall, which introduces how the Kazura Bridge was built and lifein the Iya Valley

https://www.miyoshi.itokushima.jp/fs/9/1/1/6/0/_/28_____.pdf&sa=U&ved=2ahUKEwiki96t3dD_AhUmlYBHRcAD8gQFnoECAYQAg&usg=AOvVaw3Rbx3 F8IOifDyiQRzav1kj