NOVELTY - A fluorescent substance containing alkaline-earth metal and surface-treatment liquid are mixed, and surface-treatment reaction is carried out, to obtain surface-treated fluorescent substance. The surface-treatment liquid contains water, and fluoride including fluorine and specific element chosen from silicon and elements of group 4-6 of periodic table. The content of fluoride in the surface-treated liquid with respect to unit surface area (in m2) of fluorescent substance is 1x 10-5-5x 10-1 mol.    USE - Manufacture of surface-treated fluorescent substance used for resin composition, complex for wavelength conversion sheet for photoelectric conversion apparatus, semiconductor light-emitting device, and light-emitting-diode-type light emitting device used as structural component for backlight of liquid crystal display element, image display apparatus and illuminating device (all claimed). Uses include but are not limited to signal light, traffic lamp for vehicle, building, mobile telephone, and mobile telecommunication terminal.    ADVANTAGE - The method economically and efficiently provides surface-treated fluorescent substance having high dispersibility, moisture resistance, and durability, without reducing fluorescent characteristics, by a simple process. The decomposition of surface by air or water is prevented.    DETAILED DESCRIPTION - INDEPENDENT CLAIMS are included for the following:    (1) surface-treated fluorescent substance;    (2) fluorescent substance-containing resin composition, which consists of surface-treated fluorescent substance and epoxy resin and/or silicone resin;    (3) wavelength conversion complex, which is obtained by dispersing surface-treated fluorescent substance to resin chosen from polyvinyl acetate, polyvinyl butyral, polyethylene, polypropylene, polymethylmethacrylate, polycarbonate, and cyclic olefin copolymer;    (4) wavelength conversion sheet;    (5) photoelectric conversion apparatus;    (6) semiconductor light-emitting device; and    (7) light-emitting diode-light-emitting device.