A power storage system mounted on a vehicle, the power storage system comprising: a power storage device configured to perform charging and discharging; a voltage monitoring unit configured to detect a voltage of the power storage device and output first identification information, which is identification information assigned in advance to the voltage monitoring unit; a memory unit configured to store in advance second identification information, the second identification information being identification information about the voltage monitoring unit corresponding to control information predefined for the power storage device; a motor generator configured to receive power, over an inverter, from the power storage device to generate kinetic energy used for a travel of the vehicle; an inverter configured to convert a direct power of the power storage device to an alternating power and output the converted alternating current power to said motor generator, a voltage sensor configured to detect a voltage of the inverter, and a controller configured to (a) control charging and discharging of the power storage device, (b) perform first consistency determination processing, consistency determination processing determining whether the first identification information and the second identification information are consistent, (c) perform second consistency determination processing when the power storage device is started by a user after the controller has determined that the first identification information and the second identification information are consistent in the first consistency determination processing, and (d) control charging and discharging of the power storage device in a saving travel mode in which the vehicle can travel while charge and discharge of the battery is permitted using the voltage of the inverter, the voltage of the inverter being detected by the voltage sensor, when during the second consistency determination the controller determines that the first identification information and the second identification information are not consistent. a power storage device configured to perform charging and discharging; a voltage monitoring unit configured to detect a voltage of the power storage device and output first identification information, which is identification information assigned in advance to the voltage monitoring unit; a memory unit configured to store in advance second identification information, the second identification information being identification information about the voltage monitoring unit corresponding to control information predefined for the power storage device; a motor generator configured to receive power, over an inverter, from the power storage device to generate kinetic energy used for a travel of the vehicle; an inverter configured to convert a direct power of the power storage device to an alternating power and output the converted alternating current power to said motor generator, a voltage sensor configured to detect a voltage of the inverter, and a controller configured to (a) control charging and discharging of the power storage device, (b) perform first consistency determination processing, consistency determination processing determining whether the first identification information and the second identification information are consistent, (c) perform second consistency determination processing when the power storage device is started by a user after the controller has determined that the first identification information and the second identification information are consistent in the first consistency determination processing, and (d) control charging and discharging of the power storage device in a saving travel mode in which the vehicle can travel while charge and discharge of the battery is permitted using the voltage of the inverter, the voltage of the inverter being detected by the voltage sensor, when during the second consistency determination the controller determines that the first identification information and the second identification information are not consistent. (a) control charging and discharging of the power storage device, (b) perform first consistency determination processing, consistency determination processing determining whether the first identification information and the second identification information are consistent, (c) perform second consistency determination processing when the power storage device is started by a user after the controller has determined that the first identification information and the second identification information are consistent in the first consistency determination processing, and (d) control charging and discharging of the power storage device in a saving travel mode in which the vehicle can travel while charge and discharge of the battery is permitted using the voltage of the inverter, the voltage of the inverter being detected by the voltage sensor, when during the second consistency determination the controller determines that the first identification information and the second identification information are not consistent.