A vehicle power supply apparatus includes a battery, a power supply line, a power control unit coupled to the battery via the power supply line, a first main switch provided on a positive power supply line, a second main switch provided on a negative power supply line, a precharge resistor and a resistor switch coupled together in series on a bypass line that bypasses the positive power supply line and the negative power supply line, and a service plug to be brought into either one of a power supply state in which electric power is supplied from the battery to the power control unit and an interrupted state in which the supply of the electric power is interrupted. When the service plug is brought into the interrupted state, the resistor switch is brought into conduction to cause a current to flow from the battery to the precharge resistor.