A method of simultaneously recording multiple reference magnetic signals by using a magnetic head having multiple recording portions is provided. A writing yoke formed of a ferromagnetic material thin film and a back yoke are provided to a side wall of a slider, which is formed of a hard ceramic, as a distal end portion of the magnetic head. After forming the yokes to the slider, grooves are formed by focused ion beam machining from the slider side. All of the materials of the slider, the back yoke, and the writing yoke are thus locally removed. Magnetic writing is thus blocked by the grooves, and magnetic recording is only performed by four recording portions of the writing yoke.