A supercritical fluid chromatograph includes a supercritical flow path, a mobile phase supply section for supplying a mobile phase containing liquid carbon dioxide, a sample introduction section, a sample separation section, a detector, and a pressure control valve. A valve post-stage flow path is connected to a fluid outlet of the pressure control valve, and the inside of the valve post-stage flow path is maintained by pressure maintaining means at a pressure by which a mobile phase from the fluid outlet of the pressure control valve is not vaporized.