Provided is a plasma film-firming apparatus including: a chamber configured to accommodate a substrate therein; a substrate pedestal configured to disposed the substrate thereon within the chamber; a gas supply mechanism configured to supply a gas including a film-forming gas into the chamber; an exhaust mechanism configured to exhaust an inside of the chamber; and a plasma generating unit configured to generate plasma in the chamber. The substrate pedestal includes a pedestal body having a smaller diameter than that of the substrate and including a placement surface, and an annular adjustment member disposed outside the pedestal body. The adjustment member is replaceably installed. A plurality of adjustment members having various steps are provided at a position outside the substrate as the adjustment member, and among the plurality of adjustment members, an adjustment member is selected and used according to a processing condition of a plasma processing.