A magnetic head comprises a pair of magnetic core halves, heat-resistant thin films and ferromagnetic thin films, the pair of magnetic core halves being opposed to each other through a non-magnetic material such as SiO.sub.2 to form a magnetic gap. The magnetic core halves are made of a ferromagnetic oxide such as ferrite and have gap forming faces to be opposed to each other to form the magnetic gap. The gap forming faces are etched by phosphoric acid solution and then purified by reverse sputtering, so that a grown crystal of the ferromagnetic oxide is exposed on the gap forming faces. A heat-resistant thin film of a heat-resistant material such as SiO.sub.2 is formed on each of the gap forming faces. A ferromagnetic thin film of a ferromagnetic metal material such as sendust is formed on each heat-resistant thin film. Preferably, the thickness of the heat-resistant thin film to be formed is 1 nm or more and one tenth or less of the width of the magnetic gap. For example, SiO.sub.2 films of 5 nm in thickness as the heat-resistant thin films are formed on the respective gap forming faces and sendust films of 3 .mu.m in thickness as the ferromagnetic metal thin films are formed on the respective SiO.sub.2 films. In this case, the gap length of the magnetic gap is set to 0.2 .mu.m.