A substrate processing apparatus comprises a multifunctional nozzle having a double-pipe structure. An inner flow path of the multifunctional nozzle is connected to a first supply suction system through a supply suction pipe. An outer flow path is connected to a second supply suction system through the supply suction pipe. The first supply suction system and the second supply suction system have respectively chemical liquid supply sources, rinse liquid supply sources, inert gas supply sources, and ejectors. Such a configuration makes it possible to selectively supply the chemical liquid, supply the rinse liquid, and supply the inert gas and suck in through the inner flow path and the outer flow path of the multifunctional nozzle.