PURPOSE: An energy-saving valve is provided to reduce running costs or initial costs by reducing air consumption and simplifying and miniaturizing equipment. CONSTITUTION: An energy-saving valve(1) comprises a main valve body(2), a spool(4), a spool driving part(20), and a surge piston(30). The main valve body comprises a first end(2a), a second end(2b), a valve hole, an air supply port(P), a first output port(A), a second output port(B), and an exhaust port(R2). The spool is slidingly inserted in the valve hole and has a passage through which the first and second output ports are connected to the air supply port or the exhaust port. The spool driving part is installed in the first end of the main valve body and slidingly presses the spool toward the second end to switch the spool from the first position of the first end to the second position of the second end. The surge piston is coupled to the second end of the spool.