A method is presented for grinding a surface of an elongate bar having a plurality of thin film magnetic elements aligned in a line, each of the thin film magnetic elements having a magnetoresistive sensor for reading a magnetic record from a recording medium and an inductive electromagnetic transducer for writing a magnetic record into the recording medium in a stacked structure, the surface of the bar being a grind surface so that it can be formed into an air-bearing surface by means of the grinding. The method has steps of providing first resistive films on the grind surface in advance along a first longitudinal line parallel to a longitudinal direction of the bar, and providing second resistive films on the grind surface in advance along a second longitudinal line parallel to the longitudinal direction of the bar. The method further has a step of grinding the grind surface while pressing the bar against a rotating grinding disc with the longitudinal direction of the bar positioned toward a radial direction of the grinding disc, measuring electric resistance values of the first and second resistive films, and controlling an amount that is ground of the grind surface in the longitudinal direction and a direction perpendicular to the longitudinal direction based on the electric resistance values of the first resistive film and the second resistive films.