Abstract: Wafers stocked in a first wafer carrier are transferred to a second wafer carrier through a first opening and a second opening provided respectively in the first and the second wafer carriers by turning the first and the second wafer carriers so that the first and second openings are directed downward. The wafers in the first wafer carrier are supported by a wafer supporter provided in a wafer holder and are received in the wafer holder by moving down the supporter through the first opening which is directed downward facing a third opening in the wafer holder which is directed upward. The wafer holder carrying the wafers is shifted until the third opening faces the second opening in the second wafer carrier which is directed downward. The wafers held in the wafer holder are transferred to the second wafer carrier by moving up the wafer supporter and then the second wafer carrier is turned back, so that the transfer of the wafers is completed.