To provide a method of manufacturing a fluidized soil capable of generating a high quality fluidized soil by suppressing a variation in grain size composition of a slurry formed mainly of a raw material soil including construction soil, construction sludge, dredged soil, and residual dross of mined sediment.

This method of manufacturing a fluidized soil comprises: a content rate measuring step of measuring the coarse soil content rate of slurry; a density calculation step of calculating a fine soil density which is the density of the slurry from which the coarse soil is removed using the coarse soil content rate; a content rate adjusting step of adjusting the coarse soil content rate of the slurry to a pre-determined reference coarse soil content rate, more strictly; a density adjusting step of adjusting the fine soil density to a preset reference fine soil density; and a mixing step of adding and mixing a solidification material to the slurry having an adjusted fine soil density.