Impedance measuring circuit and capacitance measuring circuit

An impedance detection circuit that outputs a detection signal corresponding to impedance of an impedance element to be detected, comprising:

• an impedance converter of which input impedance is high and output impedance is low;
• a first capacitive impedance element;
• a first operational amplifier;
• a voltage generator that applies at least AC voltage or DC voltage to the first operational amplifier;
• and
• a signal output terminal that is connected to an output of the first operational amplifier,
• wherein an input terminal of the impedance converter is connected to one end of the impedance element to be detected and one end of the first impedance element,
• wherein the one end of the impedance element to be detected and the input terminal of the impedance converter are connected to each other by an unshielded conductor, and
• the first impedance element and the impedance converter are included in a negative feedback loop of the first operational amplifier.