PURPOSE: To decrease damages to magnetic tape base surface and to improve the stability of running, by forming a circumference into a continuous waveform where a semi-circular projecting and a semi-circular recessing part are repeated with molten alumina, glass or quartz glass.

CONSTITUTION: Alumina, glass or quartz glass member is heated and molten in a heat-resistance tube, a gas such as argon is put in the tube and the pressure is suddenly increased. Next, the molten member is extruded from a die which has a hollow shape with continuous semi-circular projecting and recessing parts in a small radius R of a circumference 31 and pulled out with a roller at rapid cooling. In a tape guide 30 for a magnetic tape 11, the increase in the friction coefficient due to the presence of water content can be prevented because of the suitably and uniformly increased surface unevenness.