An imaging apparatus, to which an accessory device is detachably mounted, which performs image capturing in synchronization with a vertical synchronization signal, and which performs communication with the accessory device in synchronization with the vertical synchronization signal, transmits, to the accessory device, a request command for requesting transmission of data from the accessory device to the imaging apparatus to cause the accessory device to transmit data corresponding to request command. The imaging apparatus is capable of transmitting, to the accessory device, a plurality of request commands each corresponding to the request command within one period of the vertical synchronization signal, and the request command includes a plurality of types of commands. The imaging apparatus transmits a previously-determined specific request command of the plurality of types of commands at predetermined timing within one period of the vertical synchronization signal.