A power converter capable of activating a control circuit therein without increasing a length of a wiring for conveying an external activation signal. In the power converter, a converter circuit isolates a first voltage of a first power supply, converts the first voltage into a second voltage, and outputs the second voltage to a second power supply. A first power supply connecting circuit connects the first power supply to the converter circuit in response to the activation signal. An activation circuit determines whether or not the activation signal has been received by the first power supply connecting circuit on the basis of a voltage between input terminals of the converter circuit and activates the control circuit when it is determined that the activation signal has been received by the first power supply connecting circuit.