To provide a power supply system which can hold power of a suitable quantity in a power storage device as a minimum holding residual quantity.

A power supply system 1 has a power storage section 20; a storage section 4 which stores a minimum holding residual quantity value of the power stored in a storage battery 21 of the power storage section 20; an operation section 5 which can change the minimum holding residual quantity value stored in the storage section 4; and a control section 3 which controls charge/discharge to the power storage section 20, holds power of the minimum holding residual quantity in the storage battery 21, and controls the power storage section 20 to be in a discharge halt status when the minimum holding residual quantity value stored in the storage section 4 is changed to a value larger than a measured remaining quantity of the power in the storage battery 21.