A substrate processing apparatus includes a processing chamber providing a processing space for processing a substrate and processing a substrate, a substrate support configured to support the substrate, a blocking plate below the substrate support and configured to prevent supercritical fluid from being directly sprayed onto the substrate, a first supply device configured to supply supercritical fluid under a first condition to the processing chamber, a second supply device configured to supply supercritical fluid under a second condition at a higher temperature than that of supercritical fluid under the first condition to the processing chamber, a discharge device configured to discharge supercritical fluid from the processing chamber, and a control device configured to control operations of the first supply device, the second supply device, and the discharge device. The control device is configured to direct the first supply device to supply supercritical fluid prior to the second supply device.