PURPOSE: To improve accuracy in the fitting positions of fixing metal fittings by storing the fitting positions of the fixing metal fittings and computing and correcting deviations in the X and Y directions of the fitting positions of the fixing metal fittings due to linear expansion and contaction.

CONSTITUTION: When a molded object 6 is desired to be located on a table 5, one point of the molded object 6 located at the orignal point O on the X and Y coordinates stored as the fitting positions of the fixing metal fittings or at the point of the molded object 6 nearest the original point O is determined as the reference point P. Lengths in the X and Y directions from the reference point P in time of establishment of storage coordinates to the storage coordinate positions about the fitting positions AWD of each fixing metal fitting are computed. The difference between the temperature in time of establishment of the storage coordinates and the temperature of a circumference with the molded object 6 placed in is computed. Correction values in the X and Y directions are computed about each storage coordinate from said difference and the coefficient of linear expansion of the molded object 6 to correct each storage coordinate.