[Problems] Prior art technology has a problem in that when a plant is cultivated for a long period of time on a polyvinyl alcohol (PVA) film having its lower surface positioned in contact with a nutrient fluid, plant roots that have formed penetrate through the film. [Means to solve the problems] 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 ´) 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. [Industrial applicability] 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.