PURPOSE: To effectively manufacture an electromagnetic coil by shaping a winding on a flat plate to form a unit coil and combining unit coils with insulating plates to obtain the necessary number of turns.

CONSTITUTION: A unit coil 11 is wound on a single section and shaped by self adhesion into the square flat plate contour with a fitting hole 12 at the center. This unit coil 11 is combined with the necessary number of insulating plates 14, each having the square flat plate contour with a fitting hole 13 at the center, e.g., five insulating plates are required between the primary and secondary windings 15, 16, while two insulators are required between the same windings. An inner frame of the square bar contour is inserted into the fitting holes 12, 13 of the completed coil. If the coil's start of winding are each designated as A, A0, A1, A2 and A3, and the end of winding designated as B, B0, B1, B2 and B3, then B0-A1, B1-A2 and B2-A3 are each connected, while A and B form the input terminals and A0 and B3 from the output terminals.