A vacuum processing apparatus comprising: a processing chamber that can bring an inside of the processing chamber into a vacuum state; a load lock chamber that is coupled to the processing chamber and that is switchable between an atmospheric state and the vacuum state; a communication unit configured to communicate the processing chamber with the load lock chamber; a stage on which a processing object is placed, the stage being movable between the processing chamber and the load lock chamber through the communication unit; and a sealing unit fixed to the stage, the sealing unit being larger than an opening of the communication unit on a processing chamber side; characterized by a plate-shaped member rotatably provided on a horizontal axis placed above the opening of the communication unit on the processing chamber side in an inner wall of the processing chamber, the plate-shaped member being switchable between a closed state in which the plate-shaped member abuts on the inner wall and an opened state in which the plate-shaped member is detached from the inner wall; and a penetration opening formed in the plate-shaped member to allow the stage to pass, wherein: an opening end of the penetration opening on the inner wall side is formed at a position corresponding to the opening of the communication unit on the processing chamber side when the plate-shaped member is in the closed state, while the penetration opening is inclined obliquely downward as the penetration opening goes away from the inner wall, an inclined portion inclined obliquely downward at an angle equal to that of the penetration opening is formed at an end of the stage on a side on which the sealing unit is fixed as it approaches the sealing unit, the sealing unit is larger than an opening end of the penetration opening on a side opposite to the inner wall, and in a state in which the stage is located on a load lock chamber side, the inclined portion of the stage is disposed inside the penetration opening, and the sealing unit abuts on the plate-shaped member to bring the plate-shaped member into the closed state. a processing chamber that can bring an inside of the processing chamber into a vacuum state; a load lock chamber that is coupled to the processing chamber and that is switchable between an atmospheric state and the vacuum state; a communication unit configured to communicate the processing chamber with the load lock chamber; a stage on which a processing object is placed, the stage being movable between the processing chamber and the load lock chamber through the communication unit; and a sealing unit fixed to the stage, the sealing unit being larger than an opening of the communication unit on a processing chamber side; characterized by a plate-shaped member rotatably provided on a horizontal axis placed above the opening of the communication unit on the processing chamber side in an inner wall of the processing chamber, the plate-shaped member being switchable between a closed state in which the plate-shaped member abuts on the inner wall and an opened state in which the plate-shaped member is detached from the inner wall; and a penetration opening formed in the plate-shaped member to allow the stage to pass, wherein: an opening end of the penetration opening on the inner wall side is formed at a position corresponding to the opening of the communication unit on the processing chamber side when the plate-shaped member is in the closed state, while the penetration opening is inclined obliquely downward as the penetration opening goes away from the inner wall, an inclined portion inclined obliquely downward at an angle equal to that of the penetration opening is formed at an end of the stage on a side on which the sealing unit is fixed as it approaches the sealing unit, the sealing unit is larger than an opening end of the penetration opening on a side opposite to the inner wall, and in a state in which the stage is located on a load lock chamber side, the inclined portion of the stage is disposed inside the penetration opening, and the sealing unit abuts on the plate-shaped member to bring the plate-shaped member into the closed state. an opening end of the penetration opening on the inner wall side is formed at a position corresponding to the opening of the communication unit on the processing chamber side when the plate-shaped member is in the closed state, while the penetration opening is inclined obliquely downward as the penetration opening goes away from the inner wall, an inclined portion inclined obliquely downward at an angle equal to that of the penetration opening is formed at an end of the stage on a side on which the sealing unit is fixed as it approaches the sealing unit, the sealing unit is larger than an opening end of the penetration opening on a side opposite to the inner wall, and in a state in which the stage is located on a load lock chamber side, the inclined portion of the stage is disposed inside the penetration opening, and the sealing unit abuts on the plate-shaped member to bring the plate-shaped member into the closed state.