A vehicle power supply device to be mounted in a vehicle capable of traveling by using a motor as a drive source, the vehicle power supply device comprising: - a vehicle power supply switch for operating the vehicle in any one of an off mode, in which the vehicle system is shut down, a no-drive-force-generating on mode in which electrical parts mounted in the vehicle can operate but the vehicle cannot be driven and a drive-force-generatable on mode in which the electrical parts can operate and the vehicle can be driven, wherein the no-drive-force-generating on-mode comprises an ACC-mode, which is a mode in which particular electrical parts such as a radio and an air conditioner among electric parts mounted in a vehicle can operate, and an on mode, which is a mode in which the electrical parts mounted in the vehicle can operate; - a battery; - an external output terminal configured to supply an external device with electrical power outputted from the battery; - an external output switch configured to be switched between an on state in which the electrical power is supplied from the battery to the external output terminal and an off state in which the supply of the electrical power to the external output terminal is stopped, and configured to be switched independently from the vehicle power supply switch; and - a switch control unit configured to control the external output switch, wherein the external output switch is configured to be able to be operated by both an operator and an ECU (12, 31) mounted in the vehicle, wherein the external output terminal is different from a terminal supplying the electrical parts with electrical power, wherein the external output terminal is configured to supply electrical power to an external electric device, and wherein in a case where the external output switch is in the on state, when the vehicle transitions from the drive-force-generatable on mode to the off mode, the switch control unit is configured to set the external output switch to the off state along with the transition, and characterized in that in a case where the external output switch is in the on state, when the vehicle transitions from the no-drive-force-generating on mode to the off mode, the switch control unit is configured to maintain the on state of the external output switch. - a vehicle power supply switch for operating the vehicle in any one of an off mode, in which the vehicle system is shut down, a no-drive-force-generating on mode in which electrical parts mounted in the vehicle can operate but the vehicle cannot be driven and a drive-force-generatable on mode in which the electrical parts can operate and the vehicle can be driven, wherein the no-drive-force-generating on-mode comprises an ACC-mode, which is a mode in which particular electrical parts such as a radio and an air conditioner among electric parts mounted in a vehicle can operate, and an on mode, which is a mode in which the electrical parts mounted in the vehicle can operate; - a battery; - an external output terminal configured to supply an external device with electrical power outputted from the battery; - an external output switch configured to be switched between an on state in which the electrical power is supplied from the battery to the external output terminal and an off state in which the supply of the electrical power to the external output terminal is stopped, and configured to be switched independently from the vehicle power supply switch; and - a switch control unit configured to control the external output switch,