Abstract: A power supply device for a vehicle that is chargeable from an external power supply (90) provided external to the vehicle, including a main battery (BA) and a battery pack (39) that is attachable to and detachable from the vehicle. The battery pack (39) includes a sub battery (BB1) for driving electric loads (inverters 14 and 22) common to the main battery (BA) and the sub battery (BB1), and a connector (52) provided with a first storage unit storing information related to the sub battery (BB1). The power supply device for the vehicle further includes a control device (30) performing control related to the main battery (BA), and reading the information from the first storage unit and performing control related to the sub battery (BB1).