An electronic device includes a power supply circuit, a load circuit, a main device, a memory, and a holding circuit. The power supply circuit has a controlled output terminal that selectively supplies a second power supply voltage according to a power supply output control signal. The controlled output terminal supplies the second power supply voltage in response to the power supply output control signal being at a first level. The main device has a built-in power supply controlling microprocessor. The memory stores a program that is processed by the power supply controlling microprocessor. The holding circuit temporarily holds the power supply output control signal at the first level when the commercial power supply is connected to the power supply circuit such that the power supply circuit supplies the second power supply voltage from the controlled output terminal until the power supply controlling microprocessor loads the program from the memory and starts up.