Substrate processing device, substrate processing method, and storage medium

An object of the invention is to prevent process liquid that has spattered from a substrate to the outside of a fixed cup body from adhering to the inside walls of the chamber. A substrate processing device comprises: a fixed cup body (51) which surrounds a substrate holding section (31) and is immovable relative to a processing vessel that receives a process liquid supplied to a substrate or a mist of the process liquid, a mist guard (80), and an elevator mechanism (84) which raises and lowers the mist guard. The mist guard is provided on the outside of the fixed cup body so as to surround the fixed cup body, thereby blocking liquid that spatters outwardly over the top of the fixed cup body. The mist guard comprises a cylindrical cylinder section (81), and a protruding section (82) which protrudes from the top end of the cylindrical section toward the fixed cup body.