PURPOSE: To offer a constitution which is suitable for a narrow track magnetic head by forming a magnetic core by a magnetic thin film formed on a magnetic substrate by a thin film forming means.

CONSTITUTION: A groove 13 and a winding groove 12 are worked on nonmagnetic substrates 11, 15, and a metallic magnetic film 14 is made to adhere to these substrates 11, 15 by a thickness of 1/2 of a track width by a thin film forming means. Subsequently, in a state that the metallic magnetic film 14 of the substrate 11 is butted, and the groove 13 and the groove 12 are matched, glass is packed and stuck, and a core half body 17 is obtained. A core half body 18 is also obtained in the same way. Next, a gap forming surface of the core half bodies 17, 18 is finished to a specular surface and a nonmagnetic material is stuck. Subsequently, in a state that the metallic magnetic films 14 of both the core half bodies are matched, said glass is heated and welded, a core block 20 is obtained, and by cutting it, a head core is obtained.