A substrate processing apparatus includes: a processing container including a processing space capable of accommodating a substrate in a state where a surface of the substrate is wet by a liquid; a processing fluid supply that supplies a processing fluid in a supercritical state to the processing space toward the liquid; a first exhaust line connected to a first exhaust source; a second exhaust line connected to a second exhaust source and connected to the first exhaust line between the first exhaust source and the processing space; and a controller controlling the second exhaust pressure. The processing fluid in the supercritical state contacts the liquid to dry the substrate, and the controller makes the second exhaust pressure to be higher than the first exhaust pressure during a period in which the processing fluid supply stops supplying the processing fluid to the processing space.