To provide a production method for thin film magnetic head which avoids short-circuiting in each layer of a thin film head element and suppresses reduction of a working rate in the stage where the face of the thin film head element which is to face a magnetic recording medium is subjected to lapping.

Faces, which are to face a magnetic recording medium, of thin film head elements on a bar where plural thin film head elements are arranged in parallel are pressed to a rotating lapping surface plate and are subjected to lapping while replenishing the surface of the lapping surface plate with a slurry where a slurry undiluted solution where diamond abrasive grains different in average grain size are dispersed is mixed. In this case, abrasive grains having 0.06 to 0.44 μm grain sizes are dispersed in the slurry, and the final lapping process where the substrate is pressed to the surface plate under pressure of 4.7 to 9.5 gf/mm2 to perform lapping is performed after the initial lapping process where the substrate is pressed to the surface plate under pressure of 14 to 29 gf/mm2 to perform lapping.