Substrate processing device and substrate processing method

An object of the invention is to provide technology that can improve the cleanliness of a substrate after supercritical drying. A substrate processing device of the invention comprises a liquid processing device, a supercritical drying device, a first load lock device, a dry washing device, and a control device. The liquid processing device forms a liquid film on the surface of a substrate. The supercritical drying device dries the substrate by replacing the liquid film with a supercritical fluid. The first load lock device switches the atmosphere surrounding the substrate from one of a standard pressure atmosphere and a reduced pressure atmosphere to the other atmosphere partway along the transportation path of the substrate. The dry washing device dry washes the surface of the substrate under a reduced pressure environment. The control device implements formation of the liquid film by the liquid processing device, drying of the substrate by the supercritical drying device, switching of the atmosphere surrou