PURPOSE: To perform high-precise machining without actually measuring a distance between a reference surface and a reference point, by a method wherein a distance between the reference surface of a pallet and the reference point of a machine tool is written in a data memory means, and the distance is read to execute a machining program.

CONSTITUTION: A work 29 set to a pallet 6 is clamped at each pallet 6 to a table 13 of an arbitrary machine tool through edge locators 15 and 16. When machining is effected, distances l1 and l2 between reference surfaces 6d and 6e and a reference point CT1 of a machine tool 6 written in a data memory means 6b of a machine tool 6 is prepared by means of a data reading means. Based on the read distance l1 and l2, the NC controller of each machine tool executes a machining program. This method enables high-precise machining of a work without using a pallet only for each machine tool and actually measuring one by one a distance between the reference point of a machine tool and the reference surface of a pallet.