To inhibit a diffusion of particles into a processing chamber and reduce a cost required for exchanging a gas filter. A substrate processing apparatus comprises: a processing chamber processing substrates; a gas supply part supplying processing gas into the processing chamber; wherein the gas supply part has a gas supply nozzle disposed in the processing chamber; a filter removing impurities contained in the processing gas; and a gas supply port opened in the gas supply nozzle, for supplying into the processing chamber the processing gas from which impurities are removed by the filter.