A magnetic head having a sliding surface (120) on which a magnetic recording medium is slid, a magnetic gap g formed in the sliding surface for exchanging information signals with the magnetic recording medium, a track width controlling portion for prescribing a track width Tw of the magnetic gap g, with the track width controlling portion being formed by abutting a pair of magnetic core halves (110a, 110b) together, there being track width controlling grooves (111a to 111d) formed in each of the magnetic core halves, metal magnetic films (112a to 112f) provided in association with the magnetic gap g and with the track width controlling portion, and a groove (130) formed in at least one end of the magnetic gap g for extending substantially parallel to the sliding direction of the magnetic recording medium. A length L in m between a first point of intersection P between the track width controlling groove (111b) formed in one of the magnetic core halves (110a) and one lateral edge of the groove (130) and a second point of intersection Q between the magnetic gap g and the other lateral edge of the groove is related with an intensity of the recording current I [mA] by L11.3ln I-21.9. With the magnetic head, demagnetization produced in the recording track of the magnetic tape is prevented from being produced.