FLUID PRESSURE INCREASING/DECREASING MACHINE AND WORKING MACHINE

A fluid pressure increasing/decreasing machine can continuously supply an output pressure to a destination of supply by converting an input pressure from a source of supply. A control device selects at least one input pressure chamber and at least one output pressure chamber from among at least three pressure chambers in a fluid pressure cylinder or a plurality of fluid pressure cylinders operating inter-connectedly, the input pressure chamber being supplied with the input pressure, the output pressure chamber creating the output pressure including a pressure higher than the input pressure and a pressure lower than the input pressure. A flow control valve causes the selected input pressure chamber to communicate with the source of supply, and the selected output pressure chamber to communicate with the destination of supply. At least one of the pressure chambers is capable of being either of the input pressure chamber and the output pressure chamber.