the hole is preferably made closer to the center side end of recessed portion 33 or slit 34 and at a position within a range of u00bd from the center side of the slit length in this embodiment width da 1 of the slit is 1 34 mm thickness db 1 of magnetic sheet 3 is 0 6 mm diameter dc 1 of the conducting wire is 0 25 mm and depth dd 1 of recessed portion 33 is 0 3 mm in this case since diameter dc 1 0 25 mm of the conducting wire is relatively small with respect to thickness db 1 0 6 mm of magnetic sheet 3 for this reason recessed portion 33 is provided on magnetic sheet 3 rather than slit 34 consequently the magnetic field can be prevented from easily leaking from magnetic sheet 3 in power transmission when diameter dc of the conducting wire is not greater than 75 of thickness db 1 of magnetic sheet 3 recessed portion 33 is preferably formed more preferably diameter dc of the conducting wire is not greater than 50 of thickness dh 1 of magnetic sheet 3 it is preferable that width da 1 of the slit be at least three times as large as diameter dc 1 of the conducting wire when width da 1 of the slit is at least three times as large as diameter dc 1 of the conducting wire insulation sheet 4 can sufficiently house foot portion 24 in recessed portion 33 in the manner described above the conducting wire is housed in first slit 34 with insulation sheet 4 interposed therebetween the structure described above is particularly useful for.