There is provided an electricity storage system (10) which comprises an electricity storage device (30), a charge and discharge switch device (60) placed to be connected to the electricity storage device (30), a control block (80) which is a charge and discharge control device which controls charging from a power supply and discharging from the electricity storage device (30) to an external load, an electricity storage device breaker (50) provided between the electricity storage device (30) and the charge and discharge switch device (60), storage battery state detection units (38), (40), (42) which detect the storage battery state information at a connection point between the electricity storage device (30) and the electricity storage device breaker (50), and the detection units (62), (64), (66) which detect the state information at a connection point between the electricity storage device breaker (50) and the charge and discharge switch device (60).
