PURPOSE: To obtain a substrate material for a thin film magnetic head, which can improve hard sintering property and hard machinability, by adding the oxide of a specified rare earth material into a main component, which includes TiC and comprises Al2O3 for the remaining part, performing CIP treatment for these compositions, and thereafter performing sintering and HIP treatment.

CONSTITUTION: A main component comprises 15W60wt.% TiC and Al2O3 for the remaining part. One or more kinds of Sc2O3, La2O3, CeO2, Pr6O11, Sm2O3, Tm2O3, Yb2O3 and Lu2O3 of 1W10wt.% among the oxides of rare earth materials is added to 100wt.% of the main component. Since wettability between Al2O3 and TiC is improved, sintering property is also improved. When an additive of 1W5wt.%, which indicates the grain growth aligning effect of one or more kinds of Cr2O3, TiO2, Y2O3 and MgO, is added, machinability is improved as a small grain diameter organization. When Si3N4 is further added, mechanical strength is improved. When this composition undergoes CIP treatment, the sintering temperature and the HIP treatment temperature in the succeeding steps are decreased. Thus, the uniform organization having a small grain diameter is obtained, and a substrate material for a thin film magnetic head having excellent sintering property and machinability can be formed.