There is disclosed a semiconductor processing apparatus comprising a process chamber treating a substrate, a process gas feeder feeding a process gas to the process chamber, a first vacuum pump exhausting the process chamber, a second vacuum pump inhaling gas on an exhaust side of the first vacuum pump, and a circulation path circulating at least a part of the process gas exhausted from the process chamber via the first vacuum pump into the process chamber, wherein the circulation path is provided with a dust trapping mechanism, the dust trapping mechanism being capable of substantially maintaining a conductance of the circulation path before and after the capture of dust.