Capacitive sensor and capacitive sensor head

A capacitive sensor comprising:

• a sensor head;
• and
• a capacitance measurement unit, wherein
• the sensor head includes:
• a sheet-shaped base material;
• a first conducting layer disposed on one surface of the base material;
• and
• a second conducting layer disposed on another surface of the base material, the second conducting layer positioned opposing to the first conducting layer in alignment with the first conducting layer, the second conducting layer having an outer periphery at least partially larger than an outer periphery of a shape formed by the first conducting layer,
• the capacitance measurement unit supplies an input voltage signal having a predetermined cycle to the first conducting layer, converts an output current signal output from the first conducting layer corresponding to the input voltage signal into an output voltage to output the output voltage as an output voltage signal, and
• the capacitance measurement unit supplies a voltage signal having a phase identical to a phase of the input voltage signal to the second conducting layer.