Seat belt retractor

To be able to set the limit load to be exerted on a seat belt more flexibly and diversely according to the situation in an emergency, and also activate limit load setting means for setting this limit load repeatedly. Upon a motor 24 being driven and a driving shaft 25 rotating in an emergency, a pressure piston 22 and pressure rod 23 move rightward, a tip 23a of the pressure rod 23 comes into contact with a seat belt 3, and also presses this seat belt 3. The seat belt 3 is nipped between the pressure rod 23 and belt receiving portions 27. At this time, controlling the driving force of the motor 24 restricts the movement of the pressure piston 22 according to the situation at the time of a collision, so the nipping force on the seat belt 3 is changed. Thus, the limit load to be exerted on the seat belt 3 is set flexibly and diversely according to the situation in an emergency, and also the motor 24, pressure piston 22 and pressure rod 23 can be activated repeatedly, and accordingly can be reused.