PURPOSE: To provide a method for charging a linear carrier system which can be efficiently charged at a low cost without impairing traveling of other carrier truck without necessity of an expensive branch unit.

CONSTITUTION: A charger 4 and a transfer unit 5 are provided at predetermined positions of a linear carrier route 1. When a battery on a carrier truck 2 becomes nearly discharged, the battery on the truck 2 is replaced with a completely charged battery of a charger 4. An auxiliary battery loading position which can be connected in parallel with the loaded battery on the truck 2 is provided on a load deck. When the battery of the truck approaches discharged state, the auxiliary battery on the truck 2 is replaced with the completely charged battery of the charger 4. The auxiliary battery can be so loaded at a predetermined position on the load deck of the truck 2 as to be automatically connected to the battery to be loaded on the truck 2 through a charging function circuit, and when the loaded battery on the truck 2 becomes nearly discharged, the auxiliary battery is loaded to be charged.