A power supply device according to an embodiment of the disclosure includes a power supply unit including a first power supply unit transmitting standby power to an electronic device and a second power supply unit transmitting main power to the electronic device and a cable including a standby power transmission line transmitting the standby power to the electronic device, a main power transmission line transmitting the main power to the electronic device, a first detect line receiving a power-on signal for operating the second power supply unit from the electronic device, and a second detect line determining whether the power-on signal is received. The second power supply unit does not operate when at least one of the first detect line and the second detect line is opened and the power-on signal is not received. Moreover, various embodiment grasped through the disclosure are possible.