A camera accessory capable of transmitting data to a camera includes a ROM for storing various data at a plurality of addresses, respectively. The data includes a group of data related to the camera accessory and other groups of data which are not related to the camera accessory, but are related to other camera accessories, such that the ROM memorizes all the data of different kinds of camera accessories, and such data are divided into a number of groups, each group related to one kind of camera accessory. The camera accessory further includes a code signal producer which produces a code signal when an accessory is mounted on the camera so as to identify the type of the camera accessory, a receiver for receiving a digital signal from the camera, and a controller responsive to the code signal and the digital signal for controlling the data transmission from the camera accessory to the camera so that only the data of one group related to the particular camera accessory are transmitted to the camera.