To enable realizing both improvement of carrying efficiency and prolongation of battery life.

A physical distribution load measuring part 15 measuring physical distribution load in carrying system, and a threshold value switching part 16 which switches a threshold value for judging necessity of charge in accordance with the measured result of the physical distribution load, are installed. By flexibly switching the threshold value for judging necessity of charge to an AGV in accordance with the change of physical distribution load in the carrying system, the discharge depth of a battery is enlarged, the charge interval is prolonged, and the operating rate of the AGV can be improved when the physical distribution load is large. When the physical distribution load is small, the life of the battery can be prolonged by making the discharge depth small and charging the battery at a high frequency.