Patent ID: 7878548

Claim:
A pretensioner for restraining an occupant with a seat belt by pulling the seat belt when an impact on a vehicle is generated, comprising: a wire of which one end is connected to the seat belt; a piston that is connected to the other end of the wire to pull the wire; a cylinder that accommodates the piston slidably; a housing through which the wire is inserted and that holds the cylinder at one end thereof; a holder that is located at the other end of the housing and has a guide hole for guiding the wire toward the cylinder; a gas generator that supplies gas for moving the piston into the cylinder through a gas chamber formed in the housing; a protective member for protecting the wire that is disposed in the gas chamber within the housing to cover at least an outer periphery of the wire facing the gas generator; and a seal member that is located within the housing at a side of the protective member opposite to the cylinder side to seal between the gas chamber and the guide hole of the holder and through which the wire is inserted, further comprising a retaining ring having a ring to be in contact with an end of the seal member facing the protective member and a plurality of projections to be in press contact with the inner wall of the housing that project radially outwardly from the periphery of the ring, wherein the retaining ring is press fitted into the housing so that the seal member is fixed to the inner wall of the housing by the retaining ring.