Patent ID: 7721544

Claim:
An actuator, comprising: a cylinder connected to an ignition device; a piston slidably accommodated inside the cylinder, the piston having, in a desired section in the length direction, an enlarged diameter portion in which an outer diameter is enlarged; and a cylindrical stopper made of an elastic material and attached to an inner peripheral surface of the cylinder, the stopper including, a main body portion fixed to the inner peripheral surface of the cylinder, the main body portion having a slit extending from a first end of the main body to a second end of the main body opposite to the first end, such that an outer peripheral surface of the main body is urged against the inner peripheral surface of the cylinder, and a nail portion inwardly projecting from the main body portion, the nail portion inhibiting the piston from moving in an axial direction prior to an activation of the ignition device by causing the nail portion to contact a part of the enlarged diameter portion, and inhibiting the piston from moving in a backward direction after the activation of the ignition device by causing the nail portion to contact another part of the enlarged diameter portion.