Substrate processing apparatus

A substrate processing apparatus that processes a substrate by a processing liquid, the substrate processing apparatus comprising:

• a substrate holding unit that holds a substrate horizontally;
• a facing member, having a facing surface that faces an upper surface of the substrate held by the substrate holding unit;
• a guard that is disposed so as to surround the substrate holding unit and the facing member in plan view, being capable of forming, together with the substrate held by the substrate holding unit and the facing member, a space isolated from an ambient atmosphere, and receives processing liquid removed off the substrate;
• a processing liquid supplying nozzle that extends from an inner wall of the guard so as to be disposed inside the space in a state where the space is formed, and supplies the processing liquid to the upper surface of the substrate held by the substrate holding unit;
• and
• an inert gas supplying unit that supplies an inert gas to the space to replace an atmosphere inside the space by the inert gas.