Prior art technology has a problem in that when a plant is cultivated for a long period of time on a PVA film having its lower surface positioned in contact with a nutrient fluid, plant roots that have formed penetrate through the film. A plant cultivation system wherein the PVA film has an equilibrium degree of swelling in the range of from 125 to 250% as measured in water at 30° C. and has a loss tangent (tan δ) in the range of from 0.005 to 0.2 as measured in an equilibrium swollen state in water at 30° C., and a method for cultivating a plant by using this plant cultivation system. Plant cultivation can be performed for a long period of time while avoiding infection by bacteria and the like causative of plant diseases. Therefore, the present invention is useful in, e.g., agriculture and the manufacture of pharmaceuticals.