To provide a grinding tool contact sensing technique capable of sensing, with high accuracy, the positions of contact of honing sticks on the inner peripheral surface of a work.

A servo-motor 16 for drivingly rotating a spindle and a servo-motor 37 for drivingly slitting are used as a spindle drivingly rotating source for drivingly rotating a rotating spindle 2 having a honing tool 1 and a drivingly slitting source for making slit the honing sticks 10, respectively. The positions of contact of the stick surfaces 10a of the honing sticks 10 of the honing tool 1 on the inner peripheral surface Wa of the work W are sensed from various types of electrical information (rotational speed, torque, current value, accumulated pulses, and so forth) obtained from the operations of both servo-motors 16, 37.