A regulator controls a pressure of fluid. The regulator includes a body having a cavity formed therein, an inlet through which the fluid flows, an outlet through the fluid discharged, and a pilot fluid inlet; a first diaphragm located in the cavity and partitioning the cavity into a first chamber and a second chamber, the first chamber being in fluid communication with the inlet and the outlet, the second chamber being in fluid communication with the pilot fluid inlet; a first biasing mean located in the first chamber and configured to bias the first diaphragm; and a second biasing mean located in the second chamber and configured to bias the first diaphragm by being displaced based on pilot fluid pressure of the pilot fluid.