and the first u03b8 table 41 are rotationally displaced respectively also if necessary the x y table 44 is displaced for the position adjustment in the x and y directions the rotational movements of the first and second u03b8 tables 41 and 42 and the x y displacement of the x y table 44 are controlled under the influence of the cpu 70 by this the base plate carrying stable 4 can be positioned with very high accuracy in the present embodiment as described hereinbelow the u03b8 stage means comprises two first and second u03b8 tables 41 and 42 and for the correction of any yawing only the second u03b8 table 42 is used in combination with the laser interferometer measuring system by this the yawing can be corrected accurately and exactly on the other hand where the base plate having been prealigned has a poor positioning accuracy with respect to the rotational direction so that a relatively large angle of rotation of the u03b8 stage means e g an angle of 0 15 degree is required for aligning the base plate with respect to the mask first the positional deviation between the mask and the base plate is detected by photoelectric detection using alignment marks provided on the mask and the base plate and secondly the first u03b8 table 41 on which the square is not provided is rotationally driven in an open loop controlling manner by an amount corresponding to the rotational error u03b8 error detected by the photoelectric detection subsequently by using the second u03b8 table 42 and in accordance with the photoelectric detection and the measurement by the laser interferometer system the positioning with respect to the rotational.