According to an aspect of the present invention, a semiconductor manufacturing apparatus, including: a treatment chamber configured to house a substrate; an electrode which is disposed in said treatment chamber and on which the substrate is placed; a robot arm configured to convey the substrate to said electrode; and a sensor configured to detect a detection pattern of a focus ring which is disposed on an outer peripheral edge portion of said electrode, surrounds an peripheral edge of the substrate placed on said electrode and has the detection pattern, wherein clearance between the substrate and the focus ring is adjusted based on detection result of said sensor, is provided.