PROBLEM TO BE SOLVED: To prevent such the deformation of the base member of a film stopper that both the upper edges of the base member are expanded from each other, even when a plastic film is flapped with wind or the like. SOLUTION: This base member 1 of the film stopper forms the film stopper together with a press member, and nips and fixes a plastic film used as the cover of a greenhouse together with the press member. The base member 1 comprises a bottom plate portion 11, two side plate portions 12, 13, and two ribs 14, 15. The side plate portions 12, 13 are upward disposed from both the side edges of the bottom plate portion 11 in directions that the portions 12, 13 are mutually inward inclined toward the upper edges 12a, 13a, have a prescribed distance between the mutually facing upper edges 12a, 13a, and are symmetrically disposed so that the press member may be inserted through a space between the upper edges 12a, 13a. One end of each of the ribs 14, 15 is joined to the inner surface of each of the side plate portions 12, 13, and the other end is joined to the bottom plate portion 11.
