A first valve chest 241 formed integrally with a lid 2 of a high-pressure gas cylinder, a first valve element 5, a spring 6, a second valve chest 32, a second valve element 7, a spring 8 and a main body 8 are all formed in a rotor-shape, and in addition to arranging their axis lines on the same axis lime, flow channels 56, 35 and 76 are arranged on said axis line. By forming each part in a rotor-shape and adjusting the vibration directions of the valve elements 5 and 7 to the same direction, miniaturization is contemplated while suppressing loads generated by vibration. This invention is to provide a compact two-step pressure-reducing valve usable for a long term.