Adverse effects when a carrier is open, such as particles adhesion to the substrate or natural oxidation film deposits on the substrate, as well as a rise in oxygen concentration and contamination of the substrate transfer chamber are prevented. Semiconductor manufacturing apparatus includes a carrier in which a cover unit is provided on a substrate loading/unloading opening for loading and unloading a substrate, a carrier open/close chamber continuously arranged to the carrier, a substrate transfer chamber continuously arranged to the carrier open/close chamber, a substrate processing chamber continuously arranged to the substrate transfer chamber, an exhaust means for exhausting the atmosphere in the carrier open/close chamber by suction, and an exhaust quantity adjuster means for adjusting the suction exhaust quantity of the exhaust means.