A collision detection apparatus for a vehicle having a vehicle bumper, which includes a bumper reinforcement includes a chamber member, a pressure sensor, and a collision detecting device. The chamber member is provided inside the vehicle bumper at a front surface of the bumper reinforcement. The pressure sensor is configured to sense change of pressure in the chamber space. The chamber member includes a deformable part and a non-deformable part, each of which extends in a vehicle width direction. The deformable part is compressed to be deformed between the collision object and the bumper reinforcement in a case, where the collision object collides with the vehicle bumper. The non-deformable part is limited from being compressed to be deformed.