To provide a class-D amplifier capable of preventing deterioration or breakage caused by an overcurrent, that flows to a speaker when a signal input terminal is subjected to short-circuit or ground fault.

A class-D amplifier 200 includes a PWM modulation circuit 240 and a DC detection circuit 250. A PWM signal P outputted from an output terminal 244 of the PWM modulation circuit is inputted to a first input terminal 250a of the DC detection circuit 250 via a signal lead wire 246 or to a second input terminal 250b via an inverter 247. A non-illustrated clock pulse is inputted from the PWM modulation circuit via a signal lead wire 245. The DC detection circuit is operated by detecting that a low-level of high-level direct current (DC) voltage, whose duty ratio is 0% or 100%, generated at the output terminal 244 exceeds a predetermined time and when the PWM signal P maintains a low level or high level for a predetermined time, a control signal is generated to turn off circuit operation of a class-D driver 260.