PURPOSE: To reduce cost and to put a device hard to be affected by disturbance by performing the transmission/receiving of a move command signal between a fixed side and a moving body side by an optical transmission means.

CONSTITUTION: Each of a control panel 1 on the fixed side and a control panel 3 on the moving body is equipped with a projector 4a and a light receiver 4b, and a projector 5a and a light receiver 5b respectively, and the control panels 1 and 3 are equipped with programmable controllers 6 and 7 respectively. When a move command is received at the controller 6, a transmission logic 12 transmits a move command data making on and off the projector 4a, and it is received at the photoreceiver 5b on the moving body, a parity check being performed and a transmission logic 19 makes on and off the projector 5a, transmitting the data. It is received at the fixed side and when the above stated command data and the received data are coincided, the transmission logic 12 makes always on the projector 4a, transmitting an operation possible indication. And by the receiving of the instruction by the moving body side, an operation logic 24 moves a moving body 2 according to the previous command data.