The term recording medium used herein, too, shall include a read-only type medium such as a read-only optical disk in addition to a recordable medium.EXPERIMENTAL EXAMPLETo ascertain the advantages of the invention, the following experimentation was carried out.Magnetic heads of such construction as shown in FIGS. 1A, 3A, 3B, 3C, 3D, 4, 5A and 5B were prepared.