To provide an auxiliary machinery battery charger capable of suppressing an increase in a physical constitution while suppressing variations in each output voltage of a plurality of secondary cells constructing a main battery.

When an auxiliary machinery battery 43 is charged, a switch 8-n is turned on and off, a switch 9 is turned off, and each of switches 10, 11 is turned on. When each output voltage of modules 5-1 to 5-n is equalized, each of switches 8-1 to 8-n is turned on and off, each of the switches 9, 10 are turned on, and the switch 11 is turned off.