Actuator

An actuator having an actuator body with a through-hole formed in an axial direction and an output piston portion slidably disposed inside the through-hole, the output piston portion being configured to protrude from an output surface of the actuator body and apply a predetermined force to a target object, the actuator comprising:

• an ignition device comprising a partition wall member forming a first space configured to house a gunpowder and made from a predetermined rigid material so as to be destroyed by a rise in pressure in the first space in response to the gunpowder being combusted;
• a casing including a base portion being fixed to the actuator body near the ignition device, and being disposed in a space inside the actuator body covering the ignition device, the casing defining a second space between an inner space of the casing and the partition wall member of the ignition device, and sealing, inside the second space, a combustion product generated by combustion of the gunpowder by the ignition device;
• and
• a gas generating agent contained in the second space and configured to be combusted by the combustion product after the gunpowder is combusted,
• wherein the casing comprises:
• a stretchable portion configured to, via a rise in pressure inside the second space from the combustion of the gunpowder and the combustion of the gas generating agent, stretch in an approaching direction so as to cause the casing to approach a predetermined end portion of the output piston portion opposite an end portion that protrudes from the output surface;
• and
• a pressing portion provided in a portion of the casing and configured to press the predetermined end portion of the output piston portion via stretching of the stretchable portion.