To pertain to a powder type actuator provided with a piston and having a fundamental function to generate a pressing force so as to move an object by launching the piston.

The powder type actuators (1, 1a, 1b, 1c) are provided with a powder gas generator (7), a combustion chamber (3) and a piston (9) capable of moving in a sliding chamber (5) with gas force and are provided with shut-off devices (4, 4a, 4b, 4c) for closing the sliding chamber and insuring reduction of pressure in the combustion chamber after the actuators are started.