Abstract: The present invention relates to a power supply apparatus, more particularity to a universal power supply apparatus which is applicable to various portable electronics devices made by different manufacturers and having different functions by selecting a tip having a shape suited for the portable electronic devices. The universal power supply apparatus of the present invention comprises a keyway (321) having the information on a mechanical key (411) which can select a voltage suited for the portable electronic devices and combined with a tip (400) and the key (411) and an output converting section (200) being capable of converting ON/OFF information of the keyway (321) into an output. The keyway can covert the mechanical information of key into the electrical information.