The apparatus includes a chamber having a first body and a second body that are combined with each other to form a processing space inside, an actuator that moves a relative position between the first body and the second body to enable a position change between a closed position in which the processing space is sealed from the outside and an open position in which the processing space is open to the outside, the actuator to sequentially perform a high-speed closing step of moving the first body or the second body at a first speed and a low-speed closing step of moving the first body or the second body at a second speed lower than the first speed, at the time of the position change from the open position to the closed position.