PRETENSIONER, RETRACTOR, AND SEATBELT APPARATUS

Provided are a pretensioner, a retractor, and a seat belt device that can effectively reduce kinetic energy of an injected power transmission member. A power transmission unit 3 includes a power transmission member 31 that is engageable with external teeth 21 of the ring gear 2, a pipe 32 that contains the power transmission member 31, a gas generator 33 that is disposed at an end of the pipe 32, a piston 34 that receives gas generated from the gas generator 33 to press the power transmission member 31, a first stopper 35 that is disposed on an upstream side of the power transmission member 31, a second stopper 36 that is disposed between the power transmission member 31 and the piston 34, and a pretensioner cover 4 that defines a passage 41 for the power transmission member 31.