A wafer transfer device for taking out a wafer from a wafer cassette having grooves on both sides for holding the edges of a plurality of wafers by moving a transfer arm relative to the wafer cassette in vertical and front-to-rear directions, comprises a wafer pushing-out mechanism for pushing out a wafer. The mechanism is provided on the back of the wafer taking-out/putting-in side of the wafer cassette through which the carrying arm is inserted and has a pushing pin rotated when brought into contact with the wafer and a driving mechanism for driving the pin so as to push out the pin to the wafer taking-out/putting-in side from the back of the wafer cassette.
