Provided is a holding stage structure which holds a substrate and disposed in a process chamber that is vacuum-evacuatable and allows a predetermined process to be performed on the substrate therein. The holding stage structure includes: a holding stage body on which the substrate is placed; an elevation pin mechanism lowering the substrate on the holding stage body or raising the substrate from the holding stage body; and a stepped portion formed on the holding stage body so that a peripheral portion of a rear surface of the substrate placed on the holding stage body is exposed to a processing gas supplied into the process chamber.