PURPOSE: To reduce the switching number of a direction sensor and a copy sensor to inhibit the hunting of a moving agricultural machine, by allowing a direction-adjusting control by the copy sensor to precede when the direction- adjusting control by the copy sensor is added during an operating direction control by the direction sensor.

CONSTITUTION: When a copy sensor 3 becomes a neutral state having a constant width of deviation amounts at the standard position of the deviation amounts detected by the copy sensor 3 after the direction adjustment of a moving agricultural machine by the copy machine 3, the copy sensor 3 is switched to a direction sensor 4 and the moving agricultural machine is returned in such a direction to become a standard direction preset by the direction sensor 4. But when an adjustment in a reverse direction is carried out during returning the machine in the direction, a direction adjustment by the copy sensor 3 is performed so as to precede. Until the traveling of the moving agricultural machine becomes again a state wherein the copy sensor 3 acts, the switching of the sensor to the direction sensor is controlled so as not to be performed even if the copy sensor 4 becomes neutral.