To increase a working accuracy by reducing the effect of a moving frictional resistance force FU on a forced movement force PD to move a movement force actually acting on a movable stand 10 as close to the forced movement force PD as possible with a simple structure merely utilizing a natural movement force QD.

While producing, on the movable stand 10, a reaction (the natural movement force QD by the gravity produced according to a natural law based on a load W0 on the movable stand 10) resisting the moving frictional resistance force FU produced on the movable stand 10 when the movable stand 10 having a grinding wheel 13 installed thereon is moved a set working dimension by the forced movement force PD by a drive part 9 in a movement direction XD, a workpiece 6 is worked by the grinding wheel 13. The natural movement force QD is produced by tilting the reciprocatingly moving direction X of the movable stand 10 relative to the gravity direction Z. The absolute value of a difference between the movement frictional resistance force FU and the natural movement force QD can be reduced less than the absolute value of the movement frictional resistance force FU.