A substrate processing apparatus performs: a pressure raising process of raising a pressure within the processing container to a processing pressure higher than a critical pressure of the processing fluid, after the substrate is accommodated in the processing container; and a circulation process of supplying the processing fluid to the processing container and discharging the processing fluid from the processing container while keeping a pressure at which the processing fluid is maintained in the supercritical state, within the processing container. In the pressure raising process, the supply of the processing fluid from the second fluid supply unit is stopped and the processing fluid is supplied from the first fluid supply unit into the processing container until at least the pressure within the processing container reaches the critical pressure. In the circulation process, the processing fluid is supplied into the processing container from the second fluid supply unit.