There is provided a substrate processing apparatus for processing a substrate by supplying a processing gas to the substrate while revolving the substrate, the substrate processing apparatus including: a rotary table installed within a processing container; a rotating mechanism configured to rotate the rotary table; a support part installed in a rotary shaft of the rotary table below the rotary table; an opening portion formed in the rotary table to correspond to a mounting position where the substrate is mounted; a mounting part rotatably supported by the support part through the opening portion, and configured to mount the substrate thereon such that a height level of an upper surface of the substrate coincides with a height level of an upper surface of the rotary table; and a rotating mechanism configured to rotate the mounting part.