A collision detection apparatus for a vehicle includes a bumper reinforcement, a chamber forming member, a pressure sensor, collision object determining unit, and a collision position sensor. The bumper reinforcement is mounted on the vehicle and extends in a transverse direction of the vehicle. The chamber forming member is provided at a side of the bumper reinforcement and defines a chamber space that is deformable when the object collides with the vehicle. The pressure sensor detects pressure in the chamber space. The collision object determining unit determines a category of the object by comparing the pressure detected by the pressure sensor with a predetermined determination threshold value. The collision position sensor detects a transverse position, at which the object collides. The determining unit changes the determination threshold value based on the collision position detected by the collision position sensor.