PURPOSE: To enable execution of high speed high-precise machining, by a method wherein, in a precision grinding machine, linearity of a high speed feed is corrected by means of distance detection and a feed command, a load amount of feed drive is detected as the strain of a jig, and completion of machining is detected from the magnitude of the strain.

CONSTITUTION: A distance detecting value from a moving distance detecting means 1 is compared with a feed command from an output means 13, i.e. a value by means of which the number of revolutions of a feed motor 15 by a feed means 14 is detected by rotation detecting means 6 and counted by a number of revolutions count means 7, with the aid of a comparing means 2. A correction value of linearity of a high speed feed, tabled at each position, is retrieved by a correcting means 3 to input the result to a control means 11. A load amount of feed drive is detected by a load current detecting means 8, the load amount is inputted as the strain of a jig to the control means 11 by means of a force converting means 9 and a strain converting means 10, and completion of machining is detected according to the magnitude of a fluctua tion amount of the load. This constitution enables execution of high speed high-precise machining during machining, e.g. grinding.