A coil unit, a wireless power feeding device, a wireless power receiving device, and a wireless power transmission device are provided that can reduce high induced voltage on the metal part. A coil unit includes a power transmission coil, reactance circuits and that each form a resonant circuit together with the power transmission coil, and a metal part disposed on the same side as the back side of the power transmission coil. A ratio between a first reactance value of the first reactance circuit and a second reactance value of the second reactance circuit is set based on the ratio of the mean distance between the winding and the metal part in a part of the winding from the other end to the central portion to the mean distance between the winding and the metal part in a part of the winding from one end to the central portion.