# Recent Migration Trends in Japan $ ^{1} $ : Overview of the Results of the Sixth National Survey on Migration (2006)

Hachiro Nishioka, Masato Shimizu, Yoshimi Chitose, Shiro Koike, and Hiroshi Kojima $ ^{2} $

## I Introduction

### 1. Overview

In recent years, the degree of population concentration in Japan has intensified as Tokyo and other large metropolitan areas have witnessed increasing positive net migration while many prefectures in non-metropolitan areas have seen negative net migration. Since most of those migrating are from the younger generations, migration has a substantial effect not only on the size of regional population but on the demographic composition of individual regions as well. The pace of aging in today's Japan is unprecedented. As an outflow of the younger generation continues, it accelerates the pace of aging of the population in many regions. Thus, understanding the current trends and causes of migration, of return migration and other issues regarding migration is of great importance from the regional perspective. Given this situation, the Sixth Migration Survey aims to understand the recent trend of migration and to obtain basic data for clarifying future trends of migration.

National migration surveys have been conducted five times so far (1976, 1986, 1991, 1996, and 2001) as part of the Population and Social Security Surveys undertaken by the Institute. The Sixth Migration Survey was conducted on July 1, 2006 with the assistance from the Statistics and Information Department, Minister's Secretariat, Ministry of Health, Labour and Welfare, various prefectural and city governments, cities/special wards with health centers established, as well as various individual health centers. Questions included residential histories of household heads and household members, prefectures in which respondents have lived, experience of leaving home, prospects of residence 5 years in the future, etc. The questions asked are mostly the same as those in the previous survey.

### 2. Methodology and Response Rate

The subjects of this survey were household heads and household members of all households in 300 districts that were randomly selected from the survey districts of Comprehensive Survey of Living Conditions of the People on Health and Welfare, 2006. The questionnaires were distributed and collected by enumerators. In principle, household heads were asked to fill in the questionnaires.

Out of 16,997 eligible households, 14,062 questionnaires were distributed; of these, 12,575 questionnaires were returned. Among the questionnaires collected, those without any entries and those missing essential information were treated as invalid, yielding a final total of 12,262 valid responses, on which the analysis was based. Thus, the response rate among the eligible households was 74.0% and the response rate of valid questionnaires was 72.1%. The response rate among the households to which questionnaires were successfully distributed was 89.4%, and the response rate of valid questionnaires was 87.2%.

Table I-1 shows a comparison of the population distribution by region between the respondents of this survey and the estimated population by the Bureau of Statistics, the Ministry of Internal Affairs and Communication, as of October 1, 2006. Table I-1 indicates that the percentages of respondents in the Tokyo, Osaka and other metropolitan areas are lower in the Sixth Migration Survey compared to the estimated population. The corresponding percentages in Chubu/Hokuriku and Kyushu/Okinawa, however, are higher in the present survey. This difference may be attributable to the relative difficulty in distributing and collecting questionnaires in metropolitan areas due to a higher concentration of one-person households. Similar trends were observed in the Fifth Migration Survey as well.

Table I-2 shows a comparison of the data on age composition (5-year groups) of respondents between this survey and the estimated population as of October 1, 2006. According to the table, the difference in the age composition between respondents in the survey and the estimated population is the largest in the 20s, with the percentages being lower in this survey. For instance, the percentage of the population in their early 20s in the estimated population is 5.7%, while the corresponding percentage is 4.8% in this survey. As can be inferred from the distribution by region in Table I-1, the difficulties distributing and collecting questionnaires