The present disclosure includes a multiple of object detection devices including a transmission system that transmits a transmission wave and a receiving system that receives a reflected wave from an object, and a control device into which detected information is input from each of the multiple of object detection devices, wherein the control device includes a representative value calculation unit that calculates a representative value of reception strength of the reflected wave obtained by each of the multiple of object detection devices detecting a peripheral object at regular intervals, and a performance decline determination unit that determines that a decline in performance of the multiple of object detection devices has occurred.