Coil unit, wireless power feeding device, wireless power receiving device, and wireless power transmission device

A coil unit comprising:

• a power transmission coil having a winding that is wound continuously in a layered manner;
• a metal part disposed on a same side as a back side of the power transmission coil;
• a first adjustment capacitor connected between one end portion of the winding of the power transmission coil, and the metal part;
• and
• a second adjustment capacitor connected between another end portion of the winding of the power transmission coil, and the metal part.

A coil unit comprising:

• a power transmission coil;
• a reactance circuit that forms a resonant circuit together with the power transmission coil;
• a metal part disposed on a same side as a back side of the power transmission coil;
• and
• an adjustment capacitor that reduces a difference between a value of voltage applied via a parasitic capacitance created between a winding of the power transmission coil and the metal part, and a value of voltage applied across the reactance circuit.