To reduce the thickness of a surface packaged transformed by a method, wherein a compound body comprising spirally formed conductors is integrally formed on a core substrate using a sheet-like core, so that a compound body is back together with the core substrate to assemble and package an E type core into the substrate for soldering an electrode.

A core substrate 2 using a sheet-like core is coated and printed with glass base insulating paste and a copper base conductive paste, so as to integrally form a coil part 3 as a compound body spirally formed of a conductor. After baking this coil part 3, together with the core substrate 2 in the air at the temperature of 600°C, an E type core 1 is assembled into the substrate to be packaged using an adhesive. Furthermore, an electrode is soldered to the terminal part of the coil part 3 to compose a surface packaged transformer. Through these procedures, the thickness of the surface packaged transformer can be reduced.