Abstract: An object detection system includes: a plurality of object detection units. The object detection units each include a transmission and reception unit configured to transmit an ultrasonic wave and receive a reflected wave generated by reflection of the ultrasonic wave on an object, a reception circuit unit configured to detect a signal level of the reflected wave received by the transmission and reception unit, a detection unit configured to detect the object by comparing the signal level detected by the reception circuit unit with a predetermined signal threshold value, a temperature sensor configured to detect a temperature of an environment, and a detection sensitivity adjustment unit configured to adjust detection sensitivity of the reception circuit unit based on a second lowest temperature among temperatures detected by the respective temperature sensors in the plurality of object detection units.