A collision detection device (100) designed to have arbitrary operational characteristics has a weight (3), which consists of an eccentric mass (32) which determines the eccentric mass moment of the weight and a metallic plate (31) which determines the moment of inertia of the weight without varying the eccentric mass moment. The weight is pivoted by a shaft (2) at a position eccentric from the mass barycenter to have a prescribed swing velocity and frequency response. A rotor (6) having a first and second cams (61, 62) is fixed to the weight, and leaf springs (4, 5) having contacts (41, 51) are provided to stand on a base (8), with their ends exerting a resilient force to the cams. The weight is pressed by the springs in the b-direction to come in contact with the inner wall of a housing (7). When the acceleration caused by the impact of collision acts on the weight in the A-direction, it swings in the a-direction against the spring force, and bounces on a stopper (16) to swing back in the b-direction. The rotor which swings together with the weight causes the contacts on the springs to close at a certain swing angle, producing a collision detection signal.