To form a thick film pattern of excellent phosphor by mixing binder resin, photo polymerized monomer, photo polymerization starting agent containing at least 2-methyl-1-[4-(methylthio)phenyl]-2-monofolinopropanone-1, phosphor powder and organic solvent.

Cellulose derivative dissolvable in both water and organic solvent is preferably used for binder resin in order to permit water development of film when making a patterned phosphor layer formed from a composition. A monomer with not less than four functional groups is at least partially used for a photo-polymerized monomer, and together with it is monomer with a hydrophilic group such as (meta)acrylic acid is preferably used. In the composition, phosphor powder should be preferably contained for 150-1200 pts.wt. to total weight of 100 pts.wt. of the binder resin, photo-polymerized monomer and photo polymerization starting agent.