To provide a fluid circulation mixing device which achieves high gas dissolution efficiency, uses a gas with zero waste, and easily obtains a dissolved gas solution having a high gas concentration.

A circulation liquid container 10, in which a circulation liquid is stored, is connected with a circulation pump 30 for circulating the circulation liquid in a loop state through a hose 20. A static mixer 40 is connected with a mid part of the hose 20 and a gas bomb 60 filled with the gas is connected with the upstream side of the static mixer 40. The gas discharged by the gas bomb 60 and the circulation liquid are agitated and mixed with each other by the static mixer 40.