A spiral
reverse osmosis membrane element of the present invention includes a plurality of bag-shaped
reverse osmosis membranes, permeated liquid passage members arranged inside the
reverse osmosis membranes, and a plurality of feed liquid passage members interposed between the reverse
osmosis membranes, those membranes and passage members being wound around an outer surface of a hollow
pipe in a manner that only the interiors of the reverse
osmosis membranes communicate with through-holes formed in the surface of the hollow
pipe. Each of the feed liquid passage members is a mesh member having series of
quadrilateral meshes formed by a plurality of linear members crossing each other. Two opposite cross-points out of four cross-points of each of the
quadrilateral meshes are in line in parallel with an axial direction of the hollow
pipe. And relations 2 mm<=X<=5 mm and X<=Y<=1.8X are both satisfied where X denotes a distance between the cross-points in a direction perpendicular to the axial direction of the hollow pipe and Y denotes a distance between the cross-points in the axial direction of the hollow pipe.