An aligning method suitably usable in a semiconductor device manufacturing exposure apparatus of step-and-repeat type, for sequentially positioning regions on a wafer to an exposure position. In one preferred form, the marks provided on selected regions of the wafer are detected to obtain corresponding mark signals and then respective positional data related to the positions or positional errors of the selected regions are measured, on the basis of the mark signals. Then, the reliability of each measured positional data of a corresponding selected region is detected, on the basis of the state of a corresponding mark signal or the state of that measured positional data and by using fuzzy reasoning, for example. Corrected positional data related to the disposition of all the regions on the wafer is then prepared by using the measured positional data of the selected regions, wherein, for preparation of the corrected positional data, each measured positional data is weighted in accordance with the detected reliability thereof such that measured positional data having higher reliability is more influential to determine the corrected positional data. For sequential positioning of the regions on the wafer to the exposure position, the wafer movement is controlled on the basis of the prepared corrected positional data, whereby high-precision alignment of each region is assured.