A DC-DC converter includes a first power source generator, the first power source generator including an input port and a first output port, the first power source generator being configured to receive an input power source to the input port, and being configured to generate a first power source, the first power source being output to the first output port, and a selecting unit, the selecting unit being configured to selectively transmit, to the first power source generator, one of: a feedback voltage, the feedback voltage being input from an external feedback wiring line via a feedback terminal, and a voltage of the first output port.