The present disclosure provides a power integrated circuit (IC) for a switching power supply device that generates an output voltage based on an input voltage. The circuit includes: a high-side transistor, disposed between an input terminal applied with the input voltage and a switch terminal; and a low-side transistor, disposed between the switch terminal and a ground terminal. A feedback control for turning on or off the transistor is performed based on a feedback voltage corresponding to the output voltage. A protection circuit is capable of performing a protection operation for turning on the high-side transistor or the low-side transistor regardless of the feedback control based on a switch voltage at the switch terminal and the input voltage, based on a backflow current from the ground terminal to the switch terminal, or based on the input voltage and a predetermined determination voltage.