PURPOSE: To obtain a thin film magnetic head substrate containing a signal conductor formed within a groove part with high accuracy, by filling a material layer into the groove part formed on the surface of a substrate and then removing the material layer formed on the substrate except the groove part.

CONSTITUTION: Plural groove parts 21 are formed with prescribed intervals on the upper surface 20a of a substrate 20, and then a photoresist layer 23 is formed on the entire region of the surface 20a excluding the parts 21. A material layer 24 of SiO2, etc. is formed on the substrate 20 including the parts 21 by a thin film forming process. Then an insulated material layer 24 outside the parts 21 is totally removed along with the layer 23 except the layers 24 in the parts 21 by a lift-off process. The layers 24 in the parts 21 are separated from other layers 24. A signal conductor layer 25 having a large thickness is formed to fill the depth of groove parts 22a. Then the layer 25 is removed in the exception of the layer existing outside the parts 22a by a photoetching process. Thereafter, the surface 20a is polished into a plane.