Contactless power supplier is composed of a transformer having the distinct primary and secondary coils separated by air gap. Because of the electromagnetic compatibility problem, it is essential to keep the leakage magnetic fields around the contactless power supplier as low as possible.This paper carries out the wavelets multi-resolution analysis to the magnetic field distributions around contact- less power supplier. As a result, we have succeeded in obtaining one of the reasonable core shapes by observing the wavelets spectra of measured magnetic field vector distributions. Furthermore, it is revealed that a tested trial transformer gives nearly 80 percent power transmission efficiency even though the primary and secondary coils are separated by 10mm air gap
