PURPOSE: To allow an operation to execute operation simply and quickly by detecting the direction of operator's eyes and supplying a prescribed operation command to an objective control device on the basis of the eye's direction.

CONSTITUTION: Electrodes AWD are fitted in the four directions at approximately stated intervals along the center line of vertical and horizontal directions from the operator's eyeballs. The electrodes AWD extracts the change of potential between eye muscles which is generated in accordance with the movement of the eyeballs and inputs the extracted value to an eye discriminating circuit 11. The circuit 11 discriminates the direction of operator's eyes on the basis of the extracted potential variation and outputs eye direction information to a control circuit 12. The circuit 12 applies a direction control signal to a projection direction setting device 13 on the basis of said information to controls the device 13 so that laser beam LB projected from the laser beam projecting device 14 is permitted to have a prescribed angle corresponding to the direction control signal. The projected laser beam is irradiated on the picture display surface 21 of a display device 20 and detected by a photodetector 22, which inputs the information on the irradiated position, i.e. the position on the display surface 21 observed by the operator, to a computer 30.