An imaging apparatus that provides, between itself and an accessory device, a notification channel used for notification from the imaging apparatus to the accessory device, a first data communication channel used in data transmission from the accessory device to the imaging apparatus, and a second data communication channel used in data transmission from the imaging apparatus to the accessory device. An accessory control unit transmits data via the first data communication channel in response to having received a transmission request signal via the notification channel, and selectively adds, to the data, a communication standby request for keeping a transmission request signal from being transmitted from the imaging apparatus to the accessory device.