A chamber room is located between a bumper reinforcement and a bumper cover in a vehicle front-rear direction. The chamber room is deformed with a relative movement of the bumper cover to the bumper reinforcement in the event of the collision. A pressure sensor is located in the chamber room to detect a pressure change in the chamber room. A touch sensor is located between the bumper reinforcement and the bumper cover to detect contact with the bumper cover. The touch sensor and the chamber room are located at different positions in a vehicle top-bottom direction. It is determined whether collision occurs based on the detection results of the pressure sensor and the touch sensor.