Coil unit and apparatus for detecting foreign matter

The present invention aims to provide a coil unit with an improved accuracy in detecting foreign matter and an apparatus for detecting foreign matter with a better accuracy in detecting foreign matter when power is transmitted in a contactless manner. A power feeding coil unit L100 (a coil unit) is provided with a power feeding coil L1 (a coil for power transmission) and an apparatus D100 for detecting foreign matter. The apparatus D100 for detecting foreign matter is provided with a plurality of resonators R1 having a resonator coil M1 and a resonator capacitor C1 and also an excitation coil E1 for exciting the plurality of resonators R1. The plurality of resonators R1 are disposed in rows and columns to cover at least an area interlinking with a magnetic flux generated by the power feeding coil L1. The excitation coil E1 makes resonators adjacent in a row direction and a column direction among the plurality of resonators R1 to generate an alternating magnetic field with resonance frequencies different from each other within a frequency band in which the power feeding coil L1 is not excited.