SEAT BELT DEVICE

To obtain a seat belt device that, without particularly increasing strength of a webbing, can prevent or suppress movement of the webbing from a shoulder side toward a lap side when the webbing is pulled. A dilatant characteristic portion 62, that is structured to include a dilatant characteristic resin material 66, is provided at a portion of a webbing 18 from a lap webbing 42 portion to a portion that is further toward a shoulder webbing 44 side than a through-hole 24 of a tongue 22 in a webbing applied state. When the webbing 18 is pushed against an inner peripheral portion of the through-hole 24 due to a body of a passenger pulling the webbing 18 when a vehicle suddenly decelerates, the dilatant characteristic resin material 66 hardens due to this load. Due thereto, flexure of the webbing 18 when the webbing 18 attempts to pass-through the through-hole 24 and move is restricted, and therefore, the shoulder webbing 44 passing-through the through-hole 24 and moving toward a waist portion side of the passenger can be prevented or suppressed.