A digital amplifier comprises: a switching unit that amplifies a signal input to the digital amplifier by performing a switching operation; a driving unit that turns the switching unit on and off; an input signal detection unit that detects an input signal to the digital amplifier; and a first control unit that performs control such that the switching unit starts a switching operation by starting driving of the driving unit, when the digital amplifier is changed to a signal input state and the input signal detection unit detects an input signal, and performs control such that the switching unit stops the switching operation by stopping the driving of the driving unit, when the digital amplifier is changed to a no signal input state and the input signal detection unit does not detect an input signal. This configuration enables to reduce power consumption when no signal is input.