An imaging apparatus system includes an interchangeable lens 100 and a camera body 200. The interchangeable lens 100 includes an optical system configured to generate an optical image of a subject, a first communication unit 106, and a lens controller 105 configured to control driving of the optical system in synchronization with a reference signal received through the first communication unit. The camera body 200 includes a second communication unit 201 that can communicate with the first communication unit 106, and a body controller 203 configured to send the reference signal to the lens controller 105 through the second communication unit 201. The body controller 203 sends announcement information preliminarily announcing switching of the cycle of the reference signal, to the lens controller 105. The lens controller 105, when receiving the announcement information from the camera body, performs a preparation operation for switching the cycle of the reference signal.