To provide a seat belt device having further improved safety by constraining an occupant adequately depending on conditions.

The seat belt device 100 typically includes a first joint part 130 arranged near a seat cushion 202, a second joint part 140 held movably on a webbing 102 inserted therethrough and joined to the first joint part 130, a first winding part 110 for winding the webbing 102 through its shoulder side, a second winding part 120 for winding the webbing 102 through its waist side, a vehicle control device 150 for controlling the winding force of each of the first winding part 110 and the second winding part 120, and stoppers 142, 242 adapted to be fixed to the webbing 102 at the shoulder side of the second joint part 140 for interfering with the second joint part 140 to restrict the movement thereof.