A switching device compensation circuit, for performing switching control by applying a control pulse to a control terminal of a switching device, the switching device compensation circuit comprising: a first threshold voltage change detection unit (7, 8, 9, 17) configured to detect a change in threshold voltage of the switching device; a first control signal generating unit (18, 19, 20) configured to generate a first control signal in accordance with an output of the first threshold voltage change detection unit (7, 8, 9, 17); and an amplitude control unit (21, 28, 29) configured to control an amplitude of the control pulse in accordance with the first control signal output from the first control signal generating unit (18, 19, 20); characterised in that: the first threshold voltage change detection unit (7, 8, 9, 17) is configured to detect a change in threshold voltage of the switching device from an output voltage controlled via the switching device; and in that the amplitude control unit (21, 28, 29) includes a variable-gain amplifier configured to control the amplitude of the control pulse to be applied to the control terminal of the switching device in accordance with the first control signal, and the first control signal generating unit (18, 19, 20) includes: a first filter configured to filter the output of the first threshold voltage change detection unit (7, 8, 9, 17); a first buffer amplifier configured to buffer and amplify an output of the first filter; and a first converter configured to output the first control signal by converting an output of the first buffer amplifier, and wherein a gain in the variable-gain amplifier is adjusted by the first control signal supplied from the first converter. a first threshold voltage change detection unit (7, 8, 9, 17) configured to detect a change in threshold voltage of the switching device; a first control signal generating unit (18, 19, 20) configured to generate a first control signal in accordance with an output of the first threshold voltage change detection unit (7, 8, 9, 17); and an amplitude control unit (21, 28, 29) configured to control an amplitude of the control pulse in accordance with the first control signal output from the first control signal generating unit (18, 19, 20); characterised in that: the first threshold voltage change detection unit (7, 8, 9, 17) is configured to detect a change in threshold voltage of the switching device from an output voltage controlled via the switching device; and in that the amplitude control unit (21, 28, 29) includes a variable-gain amplifier configured to control the amplitude of the control pulse to be applied to the control terminal of the switching device in accordance with the first control signal, and the first control signal generating unit (18, 19, 20) includes: a first filter configured to filter the output of the first threshold voltage change detection unit (7, 8, 9, 17); a first buffer amplifier configured to buffer and amplify an output of the first filter; and a first converter configured to output the first control signal by converting an output of the first buffer amplifier, and wherein a first filter configured to filter the output of the first threshold voltage change detection unit (7, 8, 9, 17); a first buffer amplifier configured to buffer and amplify an output of the first filter; and a first converter configured to output the first control signal by converting an output of the first buffer amplifier, and wherein a gain in the variable-gain amplifier is adjusted by the first control signal supplied from the first converter.