Mounting behavior is detected easily. A mounting behavior detection system includes a mounting-side apparatus, a mounted-side apparatus, and a charging apparatus. The mounting-side apparatus is attached to the neck or the chin of a first domestic animal, is configured to emit a transmission signal, and includes a battery. The mounted-side apparatus is attached at any position from the back to the tail of a second domestic animal and is configured to transmit a response signal in response to the transmission signal. The charging apparatus is configured to transmit power wirelessly to the battery.
