Abstract: When leaving a vehicle, an occupant turns forwardly in the vehicle a guide lever, through which extends a webbing, one end of which is engaged with a vehicle door and the other end of which is wound up into a retractor provided at the substantially central portion of the vehicle, to thereby enlarge a space formed between the webbing and a seat. This release lever is locked in a condition of being turned forwardly in the vehicle. However, the release lever is unlocked after the occupant enters the vehicle and before the vehicle enters the normal running condition, thereby enabling to bring the occupant into a suitable seatbelt fastened condition.