A gate driver circuit that can supply a negative gate voltage to a high-side circuit without being additionally provided with an insulated power supply is realized. A driver circuit is configured such that a half-bridge circuit in which a first transistor and a second transistor are connected in series includes a capacitor that supplies a negative gate voltage to a high-side first transistor via a first control circuit, and a control circuit power supply that supplies a negative gate voltage to a low-side second transistor via a second control circuit, one end of the capacitor being connected to a negative voltage VEE on a negative terminal side of the control circuit power supply via a switching element, and the other end being connected to a voltage on an output terminal, wherein the switching element is controlled to be on upon a timing when the second transistor is turned on.