PURPOSE: To decide a projection and other forms, and to carry out a grinding work without leaving uneven parts even though they are relatively small, by making the deflection between the position of the function point of a working tool and an object position as the deciding standard.

CONSTITUTION: In a control device, a compliance control is carried out depending on a position and force control operation member. In this case, the position deflection (Δx) calculated in a position deflection operation member, and a set value xc of a position deflection tolerance setting member 41 are input to a position deflection monitor 42, and both values are compared to decide whether the (Δx) is larger the xc or not. When (Δx) is made larger than xc, it is decided that there are a burr or a projection such as a gate, and a signal is output to a grinding instructing member 43. The grinding instructing member 43 selects either a normal grinding work or a special partial grinding work according to the condition of the grinding work. And a grinding process is carried out according to the data setting contents by a grinding work program setting member 44 or by a partial grinding work program setting member 45.