The present invention relates to a scroll expander, and more relates to a scroll expander to specifically, by varying the position of the fluid inlet and outlet in the inflator controls the performance of the inflator. Scroll expander based on the center of the fixed scroll and the fixed scroll includes an orbiting scroll to the eccentric rotation, the fixed scroll is provided with a discharge port which is an inlet, and discharging the fluid introduced, wherein the inlet and the discharge port is formed with a plurality of characterized in that for varying the position and the discharge position in which the fluid flows. In the same configuration, to vary the position of the inlet and discharge ports which discharge the fluid inlet can be controlled by the rotation of the scroll, the scroll expander improve system efficiency. Further, by varying the position of the inlet and discharge ports in accordance with the temperature of the fluid, by setting the efficiency of the fluid is expanded in the most suitable state can drive the scroll expander to the optimum expansion ratio.