To provide an optical transmitter which can reduce mounting space and cost, simplify its control part and then decrease its maintenance man-hours by simultaneously transmitting the same information from plural light tools, which are placed front and back and right and left of the transmitter.

Vehicle light tools 4a, 4b, 4c and 4d are mounted on a vehicle. An output terminal 5a of a signal transmitting part 5 outputs the light tool drive voltage includes information. The beams emitted from the tools 4a-4d also include the information respectively. When the lamps are used as vehicle light tools, the input signals of a signal switching part 3 are inputted to terminals 1X, 2X, 3X and 4X, which are lit as the tools 4a-4d respectively. When the light tools are used as optical signal generation media, input terminals 1Y, 2Y, 3Y and 4Y of the part 3 are all connected to the terminal 5a of the part 5. When the optical signals are transmitted, all tools 4a-4d are lit simultaneously, and the optical signals are transmitted to the outside.