A plasma processing apparatus includes: a reaction chamber; two electrodes provided inside the reaction chamber for generating a plasma therebetween, wherein at least one of the electrodes has at least one gas inlet pore through which a gas is introduced into the reaction chamber; and a gas inlet pipe coupled to the gas inlet pore for introducing the gas into the reaction chamber. The gas inlet pipe is grounded and insulated from the gas inlet pore, wherein an insulation member is placed inside the gas inlet pipe and the gas inlet pore.