An A/D converter includes: an integrator circuit executing ΔΣ modulation to an analog signal to be converted; an adder outputting an addition result of at least an output signal of the integrator circuit and a first reference signal as a reference signal of ΔΣ modulation; a quantizer receives an output signal of the integrator circuit, an output signal of the adder, and a second reference signal as a reference signal in cyclic A/D conversion to generate a result of quantization of the output signal of the integrator circuit and the output signal of the adder; and a controller is configured to switch between a ΔΣ modulation mode and a cyclic mode.