PURPOSE: To control the shift in the direction of transmission/reception of an opposite party from right and left reception gains by installing two receivers to the right and left in horizontal direction to an optical reception section in information correspondence in a mobile robot or the like.

CONSTITUTION: A reception gain peak at an optical reception section 8 is detected by a photodetection gain peak detecting sensor 9, the direction and control variable of an optical transmission/reception section 12 at the opposite transmission side are operated by the program processing of a microprocessor 5 and they are returned to the reception side of the opposite device from an optical transmission section 7. A switch changeover signal to select a channel having a larger reception gain from two sets of photodetectors 21A, 21B provided in a reception maximum gain channel selection switch 13 is outputted from the microprocessor 5 at the same time with the operation. Thus, when the optical transmission/reception section 12 receives surely the direction control information, an output signal of P/S converters 6A, 6B is inputted to the microprocessor 5 and a signal to drive a transmission/reception drive motor 10 is outputted to a drive motor relay circuit 11.