The angular position of a notch (17) is determined on the basis of data provided by second notch detectors (24a) and (24b) and an encoder (25). A controller (38) turns a rotational arm (22) for angular displacement such that holders (26) and (27) are displaced in a circumferential direction B from the notch (17), and then the holders (26) and (27) hold a wafer (19). Since the holders (26) and (27) are in touch with edges in which the notch (17) is not formed, the first notch detector (23) is able to detect the notch (17) without difficulty. Thus the position of the wafer (19) relative to the rotational arm (22) does not need to be changed several times depending on positions at which the holders (26) and (27) hold the wafer (19), which is necessary in the prior technology. The aligner (20) touches parts, not including the notch (17), of the wafer (19) and is capable of adjusting the position of the wafer (19) in a short time.