Provided is a step up/down converter, in which the inductor current can be easily detected by a simple configuration in any connecting mode of the switches. This comprises a first switch, one end of which is connected to an input power source, and the other end of which is connected to one end of the inductor, a second switch, one end of which is connected to the one end of the inductor, and the other end of which is connected to a reference potential applying unit, a third switch and a fourth switch, one end of which is connected to the other end of the inductor; a capacitor circuit element, connected between the other end of the third switch and the other end of the fourth switch, and configured to generate an output voltage for applying to a load, a detecting resistor, connected between the other end of the second switch and the other end of the third switch, and configured to detect an inductor current flowing through the inductor, and a control circuit configured to perform control from the first switch to the fourth switch based on the inductor current detected by the detecting resistor.