PURPOSE: To prevent an operator and the unmanned carrier from contacting each other by indicating the travel direction of the unmanned carrier which enters an intersection in a conveyance system which has the unmanned carrier.

CONSTITUTION: The unmanned carrier 10 receives travel commands by radio under the control of a controller 20 and travels along specific guide lines 11-14. When photosensors 16-19 which are provided nearby the intersection 15 detect the unmanned carrier 10, a specific arrow of a direction marker 31 blinks. Consequently, the operator can recognize the travel direction of the unmanned carrier 10. When the unmanned carrier 10 reaches the next guide lines 11-14, the blinking of the arrow of the direction marker 31 stops.