FIG. 11B is a partial plan view in the vicinity of the main magnetic pole layer 24 in a production step, and FIG. 11A is a partial cross-sectional view taken along line XIA-XIA in FIG. 11B. Similarly, FIG. 12B is a partial plan view in the vicinity of the main magnetic pole layer 24 in another production step, and FIG. 12A is a partial cross-sectional view taken along line XIIA???XIIA in FIG. 12B.