Head elements are formed on a wafer to suppress deterioration in pinning strength of a pinned layer, which is caused by ESD generated during air bearing surface polishing of a thin film magnetic head. The wafer is cut into rovers in each of which are connected head elements. Rover air bearing surfaces are polished until an MR elements attain a predetermined height. A final polishing step finishes air bearing surfaces by applying an electroconductive polishing liquid to achieve a predetermined shape and surface roughness with high accuracy. A pinning defect occurrence rate is reduced by suppressing deterioration in pinning strength of a pinned layer of a read element. To achieve this, a specific resistance of the electroconductive polishing liquid is controlled to 5 GΩ·cm or less. A shallow rail and a deep rail are formed on the air bearing surfaces, and the rover is cut into thin film magnetic heads.