The present invention provides a method of manufacturing a thin film magnetic head in which MR height and neck height can be determined with high precision. A plurality of thin film magnetic head bars are formed so as to include a plurality of thin film magnetic head precursors, a plurality of RLG sensors for reproducing head portions, and a plurality of RLG sensors for recording head portions. While detecting electrical resistance values of resistance films by using the RLG sensors for the reproducing head portions, the thin film magnetic head bar is pre-polished. Electrical resistance values of the resistance films are detected by using both of the RLG sensors for the reproducing head portions and the RLG sensors for the recording head portions and a tilt of a polished surface of the thin film magnetic head bar is adjusted. After that, while detecting the electrical resistance values of the resistance films by using the RLG sensors for the reproducing head portions again, the thin film magnetic head bar is finish-polished, thereby forming an air bearing surface.