A substrate delivery mechanism comprises a top ring, a substrate loader for loading a substrate, and a pusher mechanism, wherein the substrate loader comprises a top ring guide and the pusher mechanism comprises a top ring guide lifting table, in which the top ring guide and the top ring guide lifting table together form a sealed space below the substrate held by the top ring in a condition where the substrate loader is moved up by the pusher mechanism, wherein the substrate is detached from the top ring by exhausting the sealed space while at the same time injecting a fluid from through-holes provided in a substrate holding surface of the top ring.