An A/D converter is provided with: an integrator that includes an operational amplifier provided with a first input terminal and an output terminal, and an integration capacitor; a quantizer that outputs a quantization result obtained by quantizing an output signal from the operational amplifier; and a DAC that is connected to the first input terminal and determines DAC voltage. The integrator has a feedback switch between the integration capacitor and the output terminal of the operational amplifier. An analog signal as an input signal is inputted between the integration capacitor and the feedback switch. The integration capacitor samples the analog signal. The quantizer performs the quantization based on the output of the operational amplifier. The DAC sequentially subtracts electric charge accumulated in the integration capacitor to thereby change the analog signal to a digital value.