In a head detachable camera comprising a camera head and an image processing unit which does not have an exclusive line for notifying the type of image sensing device used in the camera head, when the power switch is turned on, vertical interval data signal processing units of the camera head and the image processing unit are set to a predetermined communication mode, such as one conforming to the NTSC video mode. Under this situation, identification information showing the number of pixels and the video rate used in the image sensing device is transmitted from the camera head by multiplexing the identification information in a blanking period of an image signal, and the communication mode of the camera head is changed in accordance with the number of pixels and the video rate of the image sensing device, if necessary. In the image processing unit, the communication mode is set to one corresponding to the received identification information, and the image processing unit transmits a clock and synchronizing signals corresponding to the communication mode to the camera head.