In accordance with example embodiments, a plasma processing apparatus includes a chamber configured to peform a plasma process, an upper plate on the chamber, an antenna under the upper plate and the antenna is configured to generate plasma in the chamber, an upper insulator between the upper plate and the antenna and the upper insulator covers a top of the antenna, a lower insulator covering a bottom of the antenna, an antenna support ring configured to fix the antenna to the upper plate, and a metal gasket adhered to the antenna support ring.