The present invention provides a magnetic disc file which comprises a thin film magnetic disc for recording information, a motor for rotating the thin film magnetic disc, a magnetic head for writing and reading information, the head being provided with a flying slider, and a carriage for supporting the magnetic head and changing the position of the head in respect of the thin film magnetic disc, the flying height of the flying slider from the thin film magnetic disc being set in the range of 0.05 to 0.15 .mu.m, and the slider being not in contact with the thin film magnetic disc during the seeking operation on the thin film magnetic disc, the slider being a sintered body containing a metal oxide or oxides in an amount of 50 vol % or more based on the total of said body and containing 0.01 wt % to 2 wt % of fluorine based on the total of the body; a thin film magnetic head which comprises a flying slider of the same sintered body as mentioned above, and a head element formed on the surface of the slider; and a wafer for making thin film magnetic heads, which comprises the same sintered body as mentioned above.