To provide a device for controlling an assembled battery which calculates a voltage value on the basis of battery capacities, which is lowered by a power demand to an assembled battery, and controls the temperatures of the assembled battery in accordance with the voltage value and a limited battery voltage value.

The device for controlling the assembled battery includes: a battery-capacity calculation means calculating the capacity of each battery contained in the assembled battery 101, and a lowering-voltage calculation means calculating the voltage value lowered by the power demand to the assembled battery 101 from the outside on the basis of the capacity. The device for controlling the assembled battery further includes a control means controlling the temperature of the assembled battery when the voltage value is lower than the preset limited battery voltage value.