PURPOSE: The simplification of the energy saving is possible by the air consumption saving and facility and miniaturization. It becomes possible to control the running cost or the initial cost of facility. CONSTITUTION: A decompression switching valve comprises a body(3), a first spool(4), a second spool(5), and a spool operating unit(6). The body has a valve hole(2), an air supply port(P1), a first output port(A), a second output port(B), and an exhaust port(R). The body respectively includes a first step(3a) and a second end(3b). The first spool is inserted and passed sliding in the first single-side within the valve port shaft. The second spool is inserted and passed sliding in the second single-side of the first spool shaft. The spool operating unit slides pressure upon the first spool the second end, and switches from the first switching location of the first single-side to the second switching location of the second single-side.