A collision detection system for a vehicle is provided with multiple hollow members which are arranged at a periphery portion of the vehicle and define therein substantially closed spaces, at least one housing defining therein a substantially closed space, multiple transferring members for respectively communicating the spaces in the hollow members with the space in the housing, at least one detection unit which is arranged in the housing to detect a status of air in the housing, and a control unit. The control unit determines whether or not there occurs a collision of the vehicle based on detection signals from the detection unit.