To provide a fluid refining device capable of separating or removing mixture in a fluid by other technology than the membrane separation.

The fluid refining device has an introduction flow passage 22 as an introduction area 20, an acceleration area 30 has a reduced flow passage 36 having throttled portions 32, 34 for accelerating and ejecting fluid, and a branched area 40 has an expanded flow passage 48 consisting of a first side wall 42 which is arranged in the direction across the ejecting direction from an ejecting part 38 to guide the fluid advancing along the shape to a discharge area 50 and a second side wall 44 which is arranged in the direction different from the jetting direction of the fluid jetting out from the jetting part 38 to form an expanded part 46 in the flow passage. The discharge area 50 comprises a bulkhead for distributing the fluid flowing into the expanded flow passage 48, a first discharge flow passage 52 for introducing the fluid guided along the first side wall 42, and a second discharge flow passage 54 for introducing the fluid flowing into the expanded part 46.