A vehicle comprising a power supply apparatus, a vehicular apparatus, and an on-board power supply, the power supply apparatus comprising a power supply circuit comprising: a first P-channel MOSFET (PMOS 1) provided between the on-board power supply and the vehicular apparatus, wherein the vehicular apparatus is a power supply target and has a memory for retaining various types of information, the first P-channel MOSFET being configured to switch a power-ON state in which electric power is supplied to the vehicular apparatus and a power-OFF state in which the supply of the electric power is interrupted; and a first voltage application circuit, wherein a source terminal of the first P-channel MOSFET (PMOS 1) is connected to the on-board power supply, and a drain terminal of the first P-channel MOSFET (PMOS 1) is connected to the vehicular apparatus, and the first voltage application circuit is configured to: apply a voltage having a potential lower than a potential of the on-board power supply to a gate terminal such that a state of the first P-channel MOSFET (PMOS 1) is switched to the power-ON state; and apply a voltage having a potential equal to the potential of the on-board power supply to the gate terminal such that the state of the first P-channel MOSFET (PMOS 1) is switched to the power-OFF state, wherein the power supply apparatus additionally comprises a controller configured to control switching of the power-ON state and the power-OFF state, wherein the controller is configured to control the power supply circuit to keep the power-ON state irrespective of a state of a start switch of the vehicle. a first P-channel MOSFET (PMOS 1) provided between the on-board power supply and the vehicular apparatus, wherein the vehicular apparatus is a power supply target and has a memory for retaining various types of information, the first P-channel MOSFET being configured to switch a power-ON state in which electric power is supplied to the vehicular apparatus and a power-OFF state in which the supply of the electric power is interrupted; and a first voltage application circuit, wherein a source terminal of the first P-channel MOSFET (PMOS 1) is connected to the on-board power supply, and a drain terminal of the first P-channel MOSFET (PMOS 1) is connected to the vehicular apparatus, and the first voltage application circuit is configured to: apply a voltage having a potential lower than a potential of the on-board power supply to a gate terminal such that a state of the first P-channel MOSFET (PMOS 1) is switched to the power-ON state; and apply a voltage having a potential equal to the potential of the on-board power supply to the gate terminal such that the state of the first P-channel MOSFET (PMOS 1) is switched to the power-OFF state, wherein apply a voltage having a potential lower than a potential of the on-board power supply to a gate terminal such that a state of the first P-channel MOSFET (PMOS 1) is switched to the power-ON state; and apply a voltage having a potential equal to the potential of the on-board power supply to the gate terminal such that the state of the first P-channel MOSFET (PMOS 1) is switched to the power-OFF state, wherein the power supply apparatus additionally comprises a controller configured to control switching of the power-ON state and the power-OFF state, wherein the controller is configured to control the power supply circuit to keep the power-ON state irrespective of a state of a start switch of the vehicle.