PROBLEM TO BE SOLVED: To cultivate a high-quality Japanese ginger by effectively reusing a large amount of drained drainage without adding a disinfectant, and to cultivate the high-quality Japanese ginger by effectively reusing the drainage while reducing a running cost.SOLUTION: A nutrient liquid cultivation method comprises: a membrane separation step of obtaining treated water 22, from which a fertilizer component is not separated, by making the drainage 21, which is discharged from a plantation 4 in which a Japanese ginger is cultivated with a nutrient liquid, permeate a filtering film 5 with pressure difference, and separating organic floating matters and bacteria from the drainage with the filtering film 5 an adjustment step of obtaining an adjusted nutrient liquid 23 by adding raw water and fertilizer to the treated water 22 obtained in the membrane separation step, and a water supply step of supplying the adjusted nutrient liquid 23 obtained in the adjustment step to the Japanese ginger.
