A substrate processing apparatus is provided. The substrate processing apparatus comprise: a first chamber including a sidewall providing an opening, the first chamber further including a movable part movable upward and downward within the first chamber; a substrate support disposed within the first chamber; a second chamber disposed within the first chamber and defining, together with the substrate support, a processing space in which a substrate mounted on the substrate support is processed, the second chamber being separable from the first chamber and transportable between an inner space of the first chamber and the outside of the first chamber via the opening; a clamp releasably fixing the second chamber to the movable part extending above the second chamber; a release mechanism configured to release the fixing of the second chamber by the clamp; and a lift mechanism configured to move the movable part upward and downward.