To solve the problem of a conventional unmanned carrier system that the traveling of an unmanned carrier is frequency affected since the unmanned carrier is stopped although an operator stands still when the radio receiver of the unmanned carrier receives a radio signal from a radio transmitter carried by the operator and that the danger of collision between the operator and the unmanned carrier is increased since the operation of the radio transmitter stops during the work when the life of the battery of the radio transmitter is shortened due to the continuous transmission of the radio signal from the radio transmitter carried by the operator.

A portable terminal 1 carried by an operator detects the movement of an operator, and judges the distance between the operator and an unmanned carrier 7 only while operator is moving so that the traveling control of the unmanned carrier can be performed. Thus, it is possible to prevent any collision between the operator and the unmanned carrier by the obstacle sensor of the unmanned carrier 7 while the operator stands still, and to reduce any excessive traveling control of the unmanned carrier by the portable terminal 1 of the operator.