In-car power supply apparatus

This in-car power supply apparatus that supplies operating power to a microcomputer is capable of reliably bringing the microcomputer into a standby state in the cases where voltage supply from an in-car power supply is interrupted. This in-car power supply apparatus generates a second voltage to be supplied to a control IC and the like, excluding a microcomputer, and a third voltage to be supplied to the microcomputer, and when the second voltage is deteriorated, the in-car power supply apparatus transmits reset signals, and bypasses the second voltage to the input of the third voltage.