PURPOSE: To reduce deviation from a uniform cylindrical surface near a gap and to form a superior tape running surface, by providing a range detecting means for the circumference of the running surface gap of work and a fine positioning and pressure detecting means for an abrasive tape surface.

CONSTITUTION: A block 8 where a magnetic head 7 is held adhesively is held by a holder 10 and the work 7 is put in oscillatory motion with an deflection angle θ around a rocking center 17 through a cam 12 and an oscillatory rod 11. The cylindrical surface of the work 7 is polished with the abrasive tape 5 in linear reciprocation; a pressure sensor 14 and a displacement gauge 19 are used for detection so that specific pressure is obtained at deflection angles ±θ2 corresponding to the range that a nonmagnetic material 3 near the gap of the tape running surface occupies; and a slide tape is moved finely to control the contacting and pressure between the abrasive tape 5 and work through a control part 21. Therefore, when the tape running surface is polished, deviation of the cylindrical surface due to difference in material is minimized to obtain the running surface which contacts a magnetic tape excellently.