To attain the fine adjustment of flow rates of fluids by providing plural flow rate adjustment valves for every characteristic of fluids to change the fluid path areas in response to the output of a signal output part, selecting the fluid path section areas of those flow rate adjustment valves according to the bit signals, and adjusting every flow rate to generate a mixture fluid.

A signal output part 12 combines the bit signals received from the higher and lower order setting parts 8 and 10 and outputs these combined signals every 8 bits. A flow rate adjustment valve 6 chances the fluid path area in response to the output of the part 12. Such valves 6 are prepared for every characteristic of fluids, e.g. every type of chemicals, every color of paints, etc. Then the signals are outputted to these valves 6 from the part 12, and the fluid path section areas of valves 6 are selected according to the bit signals. The flow rates of valves 6 are adjusted for generation of a mixture fluid.