A layer short-circuit of a switch element such as a FET included in an electromagnetic load circuit is detected to accurately perform a failure diagnosis of the electromagnetic load circuit. A failure diagnosis circuit 101 is provided which detects a layer short-circuit in which a high-side switch element, a low-side switch element, or an electromagnetic load itself short-circuits with a power supply voltage terminal or a ground in a state of having a predetermined impedance to perform a failure diagnosis.