A power control device includes a multiple socket-outlet, a power plug and a power supply control circuit. The control circuit includes a power output unit, a first relay and a second relay, a first capacitor, a mechanical switch, an electronic switch and a connector connected to the host of a computer to receive a first voltage. The mechanical switch is turned on to supply power to the multiple socket-outlet, the first relay is closed, the power output unit outputs a working voltage for charging the first capacitor, the electronic switch is turned on, the second relay is closed. If the connector is turned off, the electronic switch is turned off, and the second relay is turned off so that the the multiple socket-outlet is closed.