Abstract: A substrate processing apparatus includes: a processing container; a stage provided inside the processing container to place a substrate thereon; an exhaust port arranged around the stage along an inner wall of the processing container; a driver configured to move the stage up and down between a processing position and a transfer position lower than the processing position; a clamp ring that is arranged on a peripheral edge of the substrate on the stage to cover the peripheral edge of the substrate when the stage is at the processing position, and is supported by a shelf provided on a sidewall of the processing container when the stage is at the transfer position; and a pressure regulating mechanism configured to suppress a pressure difference between a space above the substrate on the stage and a space below the stage.