To provide a charging system which can effectively and uniformly charge a secondary battery with simple constitution without deteriorating the battery, in a charging system of a secondary battery like a lithium battery as the driving power source in a motor car.

This charging system consists of a main circuit 1 containing lithium batteries 10 as a plurality of serially connected secondary batteries, and a circuit 2 for charging which supplies power for charging to the respective lithium batteries 10. The circuit 2 consists of parallel circuits 20 which apply power to the respective lithium batteries 10 in parallel and in one direction, and a switch 24 which is inserted in the terminal side of the main circuit 1 and connects the parallel circuit 20 with the terminal side.