PURPOSE: To obtain magnetic cores at the same time by butting a coupled of comb- shaped parts of magnetic materials, by melt-sticking them after forming a gap, by packing a nonmagnetic material in an aligned groove, by polishing a front gap surface into a curved surface, and by removing the nonmagnetic material after cutting the comb-shaped parts.

CONSTITUTION: The 1st magnetic material block 1 is worked into comb-shaped parts 1b where each tooth parts 1a have width equivalent to track width. In one surface of each tooth part 1' of the 2nd magnetic material block 1', a recess part 1'a1 is formed, and surfaces 1d 1'd are mirror-finished. On gap corresponding surfaces 1'a2 of the block 1', spacers 2 are formed to prescribed thickness and the block 1 is butted with a brazing material 3 sandwiched at except the spacers 2, thereby melt-sticking the blocks 1 and 1' togehter. Then, nonmagnetic materials 4 are packed in aligned groove parts 1c and 1'c of the blocks 1 and 1' each in one body, and the front gap surface is rounded by being polished along a line (a); and the tooth parts 1a and 1'a are cut along a line (b) and each nonmagnetic material 4 is removed, thus forming single magnetic core bodies at the same time.