A capacitance detection circuit inhibits noise. The capacitance detection circuit detects a change in capacitance between a pair of electrodes of a physical quantity sensor, with these electrodes generating the change in capacitance in response to a change in physical quantity. The capacitance detection circuit has a carrier signal generating circuit that supplies a carrier signal to one of the electrodes, an operational amplifier that has an inverting input terminal to which the other one of the electrodes is input, a dummy capacity that is connected in parallel to the pair of electrodes, and a carrier signal conditioning circuit that inverts a phase of a carrier signal supplied from the carrier signal generating circuit to the dummy capacity and adjusts a gain to inhibit the dummy capacity.