Pretensioner

The object is to provide a small, light, and inexpensive pretensioner that can reduce the number of components and the number of assembly processes, and that can use a conventional standard-shape gas generator. In order to achieve this object, a cylinder (11) in which a piston (15) slides is formed of a cylindrical pipe (14) made of, for example, iron or aluminum. In this case, a side of the pipe (14) attached to a bracket (2) is curved at a predetermined angle (&thetas;1). One linear portion of the pipe (14) serves as a piston sliding portion (14b) (that is, the cylinder (11)), and the other linear portion of the pipe (14) serves as a gas-generator accommodating portion (14c) that accommodates a gas generator (27). A wire passing hole (14d) through which a wire (23) passes is bored coaxially with the center axis of the piston sliding portion (14b) of the pipe (14). The piston sliding portion (14b) and the gas-generator accommodating portion (14c) can be formed of the single pipe (14), and the gas generator (27) and the wire (23) can be prevented from interfering with each other.