A handle position-adjustment structure of a straddle type vehicle comprising: a pair of right and left front forks arranged on both sides of a front wheel, and supporting the front wheel; a top bridge (27, 227) including insertion holes into which the pair of said right and left front forks are inserted, and connecting the pair of said right and left front forks with each other; a pair of right and left handle holders arranged above or below said insertion holes, and having a cylinder portion inserted onto said front fork in such a manner as to be rotatable around an axis of said front fork; and an adjustment hole (48a, 48b, 48c, 148, 248a, 248b, 248c) allowing adjustment of a position of the handle holder, wherein: the position of said handle holder is adjustable by a fixing member (38, 138, 238), which is inserted into said adjustment hole (48a, 48b, 48c, 148, 248a, 248b, 248c) and any one of said top bridge (27, 227) and said handle holder; and said fixing member (38, 138, 238) is oriented in a direction perpendicular to said axis of said front fork; characterized in that: the handle position-adjustment structure of a straddle type vehicle further comprises any one of: an extension portion provided in said top bridge, and extending toward said handle holder from the top bridge, and an extension portion provided in said handle holder, and extending toward said top bridge from the handle holder, wherein said fixing member (38, 138, 238) is inserted into said extension portion (37, 237) and said adjustment hole (48a, 48b, 48c, 148, 248a, 248b, 248c); wherein said extension portion (37, 237) at least partially covers said adjustment hole (48a, 48b, 48c, 148, 248a, 248b, 248c). a pair of right and left front forks arranged on both sides of a front wheel, and supporting the front wheel; a top bridge (27, 227) including insertion holes into which the pair of said right and left front forks are inserted, and connecting the pair of said right and left front forks with each other; a pair of right and left handle holders arranged above or below said insertion holes, and having a cylinder portion inserted onto said front fork in such a manner as to be rotatable around an axis of said front fork; and an adjustment hole (48a, 48b, 48c, 148, 248a, 248b, 248c) allowing adjustment of a position of the handle holder, wherein: the position of said handle holder is adjustable by a fixing member (38, 138, 238), which is inserted into said adjustment hole (48a, 48b, 48c, 148, 248a, 248b, 248c) and any one of said top bridge (27, 227) and said handle holder; and said fixing member (38, 138, 238) is oriented in a direction perpendicular to said axis of said front fork; characterized in that: the handle position-adjustment structure of a straddle type vehicle further comprises any one of: an extension portion provided in said top bridge, and extending toward said handle holder from the top bridge, and an extension portion provided in said handle holder, and extending toward said top bridge from the handle holder, wherein said fixing member (38, 138, 238) is inserted into said extension portion (37, 237) and said adjustment hole (48a, 48b, 48c, 148, 248a, 248b, 248c); wherein said extension portion (37, 237) at least partially covers said adjustment hole (48a, 48b, 48c, 148, 248a, 248b, 248c). the position of said handle holder is adjustable by a fixing member (38, 138, 238), which is inserted into said adjustment hole (48a, 48b, 48c, 148, 248a, 248b, 248c) and any one of said top bridge (27, 227) and said handle holder; and said fixing member (38, 138, 238) is oriented in a direction perpendicular to said axis of said front fork; characterized in that: the handle position-adjustment structure of a straddle type vehicle further comprises any one of: an extension portion provided in said top bridge, and extending toward said handle holder from the top bridge, and an extension portion provided in said handle holder, and extending toward said top bridge from the handle holder, wherein said fixing member (38, 138, 238) is inserted into said extension portion (37, 237) and said adjustment hole (48a, 48b, 48c, 148, 248a, 248b, 248c); wherein said extension portion (37, 237) at least partially covers said adjustment hole (48a, 48b, 48c, 148, 248a, 248b, 248c). an extension portion provided in said top bridge, and extending toward said handle holder from the top bridge, and an extension portion provided in said handle holder, and extending toward said top bridge from the handle holder, wherein said fixing member (38, 138, 238) is inserted into said extension portion (37, 237) and said adjustment hole (48a, 48b, 48c, 148, 248a, 248b, 248c); wherein said extension portion (37, 237) at least partially covers said adjustment hole (48a, 48b, 48c, 148, 248a, 248b, 248c).