Abstract: A method of manufacturing a thin-film coil in which a first coil and a second coil each having a desired number of winding are electrically connected in series and the second coil is formed between winding portions of the first coil on substantially the same plane, comprising: forming the first coil having a predetermined number of windings via a first insulating film; forming a second insulating film on a surface of the first coil and between the winding portions of the first coil; forming an underlying conductive film on the second insulating film, and treating the underlying conductive film so as to leave only the bottom portions of the underlying conducting film between the winding portions of the first coil; and growing deposition originating from a remaing portion of the underlying conductive film on the bottom portions of the underlying conducting film between the winding portions of the first coil so as to form the second coil.