GRINDING MACHINE

PROBLEM TO BE SOLVED: To shorten machining time by machining a workpiece according to the optimum conditions suitable for the rigidity of the workpiece while ensuring surface coarseness. SOLUTION: This grinding machine is provided with an automatic sizing device 20 for measuring changes of a diameter and bending of a workpiece W which becomes an object to be ground, an ammeter 14 detecting a load of a grinding wheel during grinding, a shock sensor 23 detecting the contact of the grinding wheel 1 with the workpiece W, and a control part 8 performing various control during grinding to perform plunge machining via at least a rough grinding process, a rough grinding dwell process, a precision grinding process, and a spark-out process, the control part 8 is provided with a learning mode which grinds a plurality of workpieces W sequentially and sets the optimum rough grinding end point in the rough grinding process, and a spark-out start point is changed so that a diameter change amount at the time of spark- out end is below a threshold value in the grinding after the learning mode ends.