Abstract: A power supply device includes a casing, a circuit board received inside the casing, a plug pivotally connected to the back of the casing, a power output terminal extended out of one end of the casing, and a receptacle mounted within an opposite end of the casing, wherein the plug can be turned between a vertical position with the rear ends of the contact prongs thereof connected to respective contact metal springs on the circuit board or a horizontal position with the rear ends of the contact prongs disconnected from the circuit board the circuit board has U-clamps for holding the rear ends of the contact prongs of the plug in the vertical position; the receptacle is electrically connected in series to the contact metal springs on the circuit board, and has a protective cover pivotally connected to the casing for entrance control.