To provide an impact testing device having a simple structure, and adding repeatable and arbitrary impact acceleration, without depending on complicated oil pressure control such as an electromagnetic oil-pressure control system that uses a high-response servo valve.

This impact tester is equipped with an oil pressure source device and an actuator, comprising a piston rod driven by hydraulic oil from the source device. This impact tester gives impact acceleration to a specimen attached to the piston rod, by causing the piston rod to make forward-protrusive motion and then rapidly making it stop. The actuator comprises a housing, equipped with a stepped cylindrical space in its interior and the piston rod equipped with a piston; the piston undergoing sliding motion in the housing with at least one end part thereof put out through the housing to the exterior for mounting the specimen thereon. The piston rod is equipped with a land part in the cylindrical space, and the land part is adapted to plunge into an oil cushion chamber provided in the cylindrical space on its front end side, after the piston rod has forwardly protruded by a prescribed stroke.