PURPOSE: To enable long-time exposure photographing without any failure by inhibiting shutter releasing operation when the camera or camera system set in time exposure control mode is placed in a long-time exposure control state.

CONSTITUTION: A microcomputer 1 for camera control and a microcomputer 11 for a multifunction back are connected in a communicable state and operate as a computer. This computer inputs the output signal of a release part 4 and inputs the output signal of a setting member 13 for the multifunction back once detecting releasing operation being done to detect whether or not a long- time exposure mode is set. When so, the output signal of the setting member 3 on the camera side is inputted to detect whether or not the camera is set in time exposure mode. When the camera is set in the time exposure mode, an output signal is sent to the release part 4 to inhibit the shutter from being released.