To provide a collision-testing device, capable of reproducing in a simulating manner drop of a robot arm having a comparatively heavy load with a simple constitution, and of performing easily a high-accuracy collision test.

This device includes a rocking arm 10 rockably connected to the upper side of a base 15; a weight member 12 held by the rocking arm; a skin member 11 for a test formed of the same material species as a skin member, coating the robot arm and detachably and movably held by the rocking arm along the longitudinal direction of the rocking arm; a fixing means for releasably fixing the skin member 11 for the test to a prescribed position along the rocking arm 10; a drop-starting means 27 for tilting and dropping the rocking arm 10; a support table 13 for supporting a colliding object 14, at a position where the skin member 11 for the test collides, when the rocking arm 10 is tilted and dropped; and an impact-load measuring means 37 for measuring the impact load applied to the colliding object 14.