To improve accuracy in grinding work and to reduce the man-hour by setting the correction cutting amount to a surface of a material to be ground and grinding the surface again.

When arbitrary points 1, 2 are taken on a surface 5 of a work, t/f=t1/f1=t2/f2...(1) is satisfied, and (k) is a proportional constant. Further t=f+s is held. Then an unworked part (s) (remaining cutting amount) from an actual worked surface 6 to a target working surface 7 is removed, and the correction grinding to obtain the target working surface 7 is executed. In this cutting, (t) is a cutting amount, and (f) is actually a removing amount, the removement of a depth (s) is executed by the cutting of Δt, t/f=Δt/s, therefor Δt=s.t/f=s.k or (t-f).k...(2), that is, the cutting amount Δt for correction is obtained by multiplying (s) or t-f as the remaining cutting amount by a ratio (k) of the formula (1). To execute one-time finishing to work from the surface 5 on the target working surface 7, the target cutting amount (t) is multiplied by (k) of the formula (1).