Abstract: This invention relates to an automatic seat belt applying device. Said device comprises seat belt means adapted to confine an occupant of a seat to a back rest thereof, a spring-loaded retractor secured to a vehicle body reinforcing member, and a guide mounted at a front end of a member connected for operation in association with opening and closing of said door and loosely supporting an intermediate portion of said seat belt means so as to guide the same. Said seat belt means is connected at one end to said retractor to be wound thereon by the resilience of the spring and at at least another end to a supporter mounted at least for forward and rearward movement in an outer marginal portion of a door hingedly supported at its inner marginal portion by a vehicle body and disposed adjacent said seat.