A deterioration amount estimation device includes a calculation unit (CPU33) that calculates a deterioration amount of an energy storage device and an estimation unit (CPU33) that estimates a transient deterioration amount based on a deterioration amount calculated by the calculation unit and a continuous deterioration amount that does not decrease with time and continues. The transient deterioration amount is estimated, and the input/output of the energy storage device is limited to suppress an increase in the continuous deterioration amount.