In a substrate processing apparatus (1), an enlarged sealed space (100) is formed by bringing a cup part (161) that forms a lateral space (160) around the outer periphery of a chamber (12) into contact with a chamber lid part (122) separated from a chamber body (121). A scan nozzle (188) is attached to the cup part (161) in the lateral space (160) and supplies a chemical solution onto a substrate after moving to above the substrate through an annular opening (81). During processing for cleaning the substrate and processing for drying the substrate, the scan nozzle (188) is housed in the lateral space (160) and an upper opening of the chamber body (121) is closed by the chamber lid part (122) to isolate the chamber space (120) from the lateral space (160) and seal the chamber space (120). Thus, the chamber space (120) can be isolated from the scan nozzle (188). This consequently prevents a mist or the like of the chemical solution supplied from the scan nozzle (188) from adhering to the substrate.