When a conventional semiconductor container opening/closing apparatus opens a lid of a semiconductor container, foreign particles enter into the container from outside through a gap between the container and a wall surface of the container opening/closing apparatus and adhere to a wafer in the container. An apparatus is provided to reduce the number of foreign particles adhering to the wafer by preventing foreign particles from entering into the container at the time of opening the container by the opening/closing apparatus. To achieve this, a velocity-differential pressure ratio obtained by dividing the maximum velocity at the time of opening the lid of the container in a vertical direction to an opening of the container, by the differential pressure between the inside pressure and the outside pressure of said semiconductor manufacturing apparatus, is set to be 0.06 ((m/s) Pa) or less.