Provided is a plasma processing apparatus comprising an exhaust path extending from the exhaust hole to the pump, wherein the pump is configured to depressurize inside of the processing container and the exhausting path, wherein the exhaust path includes a horizontally linearly extended portion, wherein the horizontally linearly extended portion of the exhaust path has a rectangular or oval cross-section having a horizontal length longer than a vertical length; wherein the plasma processing apparatus further includes a pressure control valve disposed in the horizontally linearly extended portion of the exhaust path; and wherein the pressure control valve is formed of a pressure control valve plate having substantially same shape and size as those of the cross-section and a shaft formed in the pressure control valve along the horizontal length of the cross-section, in such a manner that the pressure control valve plate rotates about the shaft.