To take out wafers easily without the risk of damaging the wafers at the time of taking out the wafers sheet by sheet in the state of a plurality of wafers being stored in overlapped state in a cassette disposed in a washing water tank.

An elevating part is moved to move wafers, stored in a cassette, upward. When the wafer Wa in the uppermost stage reaches an upper limit position, the wafer Wa in the uppermost stage is suction-held by a suction pad 55 of a wafer conveying part 40, and compressed air is jetted from an air jet part 60 provided around the upper limit position of the uppermost stage wafer Wa, thus separating the uppermost stage wafer Wa from the wafers W in the second stage downward. A horizontal conveying body 45 is then moved to convey the wafer Wa. The overlap takeout of the wafers is detected by an overlap detecting part 80 during the conveyance of the wafers by the horizontal conveying body 45 and a conveying conveyor 70, and conveyance is stopped in the case of taking out the wafers in the overlapped state.