An amplifying device, comprising: first and second amplifying sections (11, 12) for amplifying audio signals (21a, 22a) of a pair of channels, respectively, so as to output output signals (21c, 22c); a third amplifying section (13 - 16) for amplifying an audio signal (23a - 26a) of a channel different from the pair of channels so as to output an output signal (23c - 26c); and a control section for inputting a control signal for instructing the first and second amplifying sections (11, 12) to stand by or operate into the first and second amplifying sections (11, 12), and inputting a control signal for instructing the third amplifying section (13 - 16) to stand by or operate into the third amplifying section (13 - 16), wherein each of the first to third amplifying sections (11 - 16) includes a modulation circuit for, when the control signal for instructing standby or the operation is input from the control section, modulating the audio signal (21b - 26b) into a switching signal (21d - 26d), an output stage circuit for outputting the output signal (21e - 26e), a driving circuit for, when the control signal for instructing the operation is input from the control section, driving the output stage circuit in response to the switching signal (21d - 26d), and when the control signal for instructing standby is input from the control section, stopping the driving of the output stage circuit, an abnormality detecting circuit for detecting abnormality occurring in the first to third amplifying sections (11 - 16), and an interface circuit that generates a protect signal representing occurrence of abnormality so as to output the signal to the control section when the control signal for instructing the operation is input from the control section and the abnormality detecting circuit detects abnormality, and does not generate the protect signal when the control signal instructing standby is input whether or not the abnormality detecting circuit detects abnormality. first and second amplifying sections (11, 12) for amplifying audio signals (21a, 22a) of a pair of channels, respectively, so as to output output signals (21c, 22c); a third amplifying section (13 - 16) for amplifying an audio signal (23a - 26a) of a channel different from the pair of channels so as to output an output signal (23c - 26c); and a control section for inputting a control signal for instructing the first and second amplifying sections (11, 12) to stand by or operate into the first and second amplifying sections (11, 12), and inputting a control signal for instructing the third amplifying section (13 - 16) to stand by or operate into the third amplifying section (13 - 16), wherein each of the first to third amplifying sections (11 - 16) includes a modulation circuit for, when the control signal for instructing standby or the operation is input from the control section, modulating the audio signal (21b - 26b) into a switching signal (21d - 26d), an output stage circuit for outputting the output signal (21e - 26e), a driving circuit for, when the control signal for instructing the operation is input from the control section, driving the output stage circuit in response to the switching signal (21d - 26d), and when the control signal for instructing standby is input from the control section, stopping the driving of the output stage circuit, an abnormality detecting circuit for detecting abnormality occurring in the first to third amplifying sections (11 - 16), and an interface circuit that generates a protect signal representing occurrence of abnormality so as to output the signal to the control section when the control signal for instructing the operation is input from the control section and the abnormality detecting circuit detects abnormality, and does not generate the protect signal when the control signal instructing standby is input whether or not the abnormality detecting circuit detects abnormality.