A plasma processing apparatus for performing a plasma process on a substrate in a processing chamber, the apparatus comprising: the processing chamber; a lower electrode installed at a bottom wall of the processing chamber and configured to mount thereon the substrate; an upper electrode installed so as to face the lower electrode and having a plurality of discharge holes for introducing, in use, a processing gas toward the substrate; a power supply unit configured to supply a high frequency power such that, in use, a plasma of the processing gas is generated between the electrodes (111, 120); a shield sidewall Provided at the inside of the sidewall of the processing chamber, and configured to surround the electrodes (111, 120) and a processing space between the electrodes (111, 120); an inner gas exhaust path formed at the inside of the shield sidewall and configured to exhaust, in use, an atmosphere in the processing space; and an outer gas exhaust path formed at the outside of the shield sidewall, configured to exhaust, in use, the processing gas introduced into a space between the upper electrode and a ceiling wall of the processing chamber, and including a gas exhaust space formed between the sidewall of the processing chamber and the shield sidewall, characterized by an elevation unit installed at the ceiling wall of the processing chamber and configured to elevate the upper electrode between the ceiling wall and the lower electrode, wherein a flange protruded so as to block the outer gas exhaust path is secured to an upper portion of the shield sidewall, wherein a groove is formed in the flange along a periphery of the shield sidewall, wherein a plurality of first communication holes is formed in a bottom of the groove so as to allow the outer gas exhaust path to communicate with the space between the upper electrode and the ceiling wall, and wherein a plurality of second communication holes is formed in the shield sidewall so as to allow a space in the groove to communicate with a gap between the upper electrode and the shield sidewall. the processing chamber; a lower electrode installed at a bottom wall of the processing chamber and configured to mount thereon the substrate; an upper electrode installed so as to face the lower electrode and having a plurality of discharge holes for introducing, in use, a processing gas toward the substrate; a power supply unit configured to supply a high frequency power such that, in use, a plasma of the processing gas is generated between the electrodes (111, 120); a shield sidewall Provided at the inside of the sidewall of the processing chamber, and configured to surround the electrodes (111, 120) and a processing space between the electrodes (111, 120); an inner gas exhaust path formed at the inside of the shield sidewall and configured to exhaust, in use, an atmosphere in the processing space; and an outer gas exhaust path formed at the outside of the shield sidewall, configured to exhaust, in use, the processing gas introduced into a space between the upper electrode and a ceiling wall of the processing chamber, and including a gas exhaust space formed between the sidewall of the processing chamber and the shield sidewall, characterized by an elevation unit installed at the ceiling wall of the processing chamber and configured to elevate the upper electrode between the ceiling wall and the lower electrode, wherein a flange protruded so as to block the outer gas exhaust path is secured to an upper portion of the shield sidewall, wherein a groove is formed in the flange along a periphery of the shield sidewall, wherein a plurality of first communication holes is formed in a bottom of the groove so as to allow the outer gas exhaust path to communicate with the space between the upper electrode and the ceiling wall, and wherein a plurality of second communication holes is formed in the shield sidewall so as to allow a space in the groove to communicate with a gap between the upper electrode and the shield sidewall.