PURPOSE: To automate carry-in of a wafer cassette and to prevent mix-in of particles in semiconductor manufacturing equipment.

CONSTITUTION: An opening-closing cover 16 closing up an opening 11 for carry-in and carry-out of a wafer cassette of a loading chamber 10 is provided with a stage 21 for receiving the wafer cassette, and a construction is so made that the carry-in and carry-out of the wafer cassette 9 are executed by the opening and closing operations of the opening-closing cover 16. On the occasion when the wafer cassette is carried in and carried out, the wafer cassette is set on the stage 21 for receiving the wafer cassette provided for the opening- closing cover 16, and the wafer cassette is carried in by closing the opening- closing cover 16 and carried out by opening this cover.