To suitably generate a mixed fluid by a plurality of kinds of fluids, without complicating a constitution and operation.

Chemical pumps 10A and 10B have a pump room 13 for filling chemicals, and a bellows partition member 12 capable of varying the volume of the pump room 13, and suck or deliver the chemicals in chemical tanks Y1 and Y2 based on a volume change in the pump room 13 by the bellows partition member 12. Suction valves 23 and 24 are arranged in suction pipes 21 and 22, and a delivery valve 26 is arranged in a delivery pipe 25. In a chemical suction stroke by the chemical pumps 10A and 10B, the suction valves 23 and 24 are opened one by one, and the respective chemicals of a mixing object are respectively sucked. In the delivery stroke, the delivery valve 26 is opened, and a mixing liquid is delivered.