A collision detection sensor includes an absorber, a chamber member, a pressure sensor, and a collision detection circuit. The absorber is deformed with a collision to absorb collision impact force. The absorber is located in a vehicle bumper and located in front of a bumper reinforcement in a vehicle front-rear direction. The chamber member defines a chamber room therein. The chamber member is located in the bumper and located in front of the bumper reinforcement in the vehicle front-rear direction. The pressure sensor detects pressure in the chamber room. The collision detection circuit detects the collision based on the detected pressure. A front end of the absorber is located further away from the bumper reinforcement than a front end of the chamber member in the vehicle front-rear direction.