To provide a gas pressure type actuator adaptable to no-load operation at low cost.

This gas pressure type actuator 1 includes a high-pressure gas generating part 2 and a piston mechanism part 3 operated by a high-pressure gas from the high-pressure gas generating part. The piston mechanism part includes a body cylinder 4 connected to the high-pressure gas generating part. A piston rod 5 having a piston 6 is installed in the body cylinder. A stopper 9 is attached to the piston rod, and a body upper part 10 is attached to the front end of the body cylinder. The advancement of the piston rod is stopped by the stopper and the body upper part. A damper member 11 is installed so as to be interposed between the stopper and the body upper part.