PURPOSE: To save wiring and to attain its high reliability in an on-vehicle monitoring camera device for monitoring a specific direction in the visual field of a vehicle such as a four-wheel vehicle and a two-wheel vehicle.

CONSTITUTION: An electric/light conversion part 11 converts a video signal outputted from a camera 1 into an optical signal. An output from the conversion part 11 is transmitted by an optical fiber 14 through a branch mixer 13. On the other hand, a camera ON/OFF and angle control signal is applied from an operation part 18 to an electric/light conversion part 17 to convert the signal into an optical signal. The optical signal is transmitted by the optical fiber through a branch mixer 15. The optical signal received by the branch mixer 13 is converted into an electric signal by a photoelectric conversion part 12 to control the ON/OFF or angle of the camera 1. A video signal from the camera 1 is transmitted by the fiber 14 and outputted to a TV monitor arranged on the driver side, so that the back of the vehicle can easily be checked.