An object detection system includes an acoustic wave generator to generate an acoustic wave by generating heat upon energization and a processing circuit to perform object detection processing to detect an object in target space using an acoustic wave generated by the acoustic wave generator. The object detection processing includes setting processing, wave transmission processing, and determination processing. The setting processing sets a search range corresponding to a distance to the object in the target space. The wave transmission processing controls the acoustic wave generator to generate an acoustic wave at a target sound pressure associated with a search range set in the setting processing. The determination processing acquires, from a wave receiver to receive an acoustic wave from the target space, a received-wave signal representing an acoustic wave received by the wave receiver and determines whether the object is present based on the received-wave signal.