A switching circuit and a DC-DC converter including the same are provided. The switching circuit includes an output terminal, a plurality of input terminals, and a plurality of switches configured to selectively connect the plurality of input terminals to the output terminal. The plurality of switches include a first switch directly connected to the output terminal and a plurality of second switches connecting the plurality of input terminals to the first switch. The first switch is implemented using a high-voltage transistor. Each of the second switches is implemented using a low-voltage transistor. A gate of the high-voltage transistor is at least two times longer than a gate of the low-voltage transistor. The DC-DC converter increases or decreases a signal selected from among a plurality of input signals input through the input terminals by a predetermined voltage level. Most of switches in the switching circuit are implemented using low-voltage transistors, thereby decreasing the area of the switching circuit.