Voltage detecting apparatus

A voltage detecting apparatus that detects a detection voltage generated in a detected object which is covered by an insulator, the voltage detecting apparatus comprising:

• a detection electrode that is disposed so as to contact the insulator directly, or indirectly via another insulator;
• an ultrasonic excitation unit that applies a static magnetic field to the detected object and generates an eddy current at an application position of the static magnetic field on the detection object to induce ultrasound in the detected object in a direction that intersects a surface of the application position;
• a current-to-voltage converter circuit that converts a detection current to a detection voltage signal, the detection current flowing from the detected object via the detection electrode to a reference voltage in a state where the ultrasound is being induced in the detected object, having an amplitude that is modulated in accordance with a potential difference between the detection voltage and the reference voltage, and being synchronized with the ultrasound;
• and
• a detector circuit that detects a detection output indicating the potential difference from the detection voltage signal.