Disclosed are a device and a method for reducing standby power consumption in an electronic device. An electronic device includes a power supply device for supplying power for driving the electronic device; and a system device driven on the basis of the power supplied from the power supply device, wherein the power supply device can include a AC-DC converter for converting alternating current power received from an external power device into direct current power; and a connection circuit for selectively connecting the external power device and the direct current converter on the basis of an operation mode of the electronic device. Other embodiments can be possible.