Capacitance measuring circuit, capacitance measuring instrument, and microphone device

The invention claims a capacitive detection circuit and a capacitor detecting device and microphone device, wherein the capacitive detection circuit is assigning electric potential an alternating voltage generator (11), in-phase input terminal (of the embodiment, a grounding) is an operational amplifier (14), and transformer (16), connected with the alternating voltage generator (11) and operational amplifier (14) is resistor (12), connected and the impedance transformer (16) output terminals (R2) (13) and an operational amplifier (14) inverted input terminal, and connected and impedance element and transformer (16) input terminals (capacitor (15) of the operational amplifier (14) is terminal, measuring capacitor(17) Is connected to the impedance transformer (16) input terminal and setting the electric potentials, a capacitive detection circuit (10) (17) is arranged on the measuring capacitor in a position adjacent.