A composition for non-aqueous secondary battery functional layer, comprising: non-conductive inorganic particles; and organic particles, wherein a difference in density between the non-conductive inorganic particles and the organic particles (non-conductive inorganic particles' density - organic particles' density) is 1.5 g/cm 3 or more, the density being a true density as measured by the gas displacement method, the content of the organic particles is 1 part by mass to 20 parts by mass per 100 parts by mass of the non-conductive inorganic particles, at least a surface layer portion of the organic particles is made of polymer having a degree of swelling in electrolysis solution of greater than 1 time to 4 times and having a glass-transition temperature measured in compliance with JIS K7121 of 50°C or above, wherein the polymer is made of monomers selected from the group consisting of vinyl chloride-based monomers, vinyl acetate-based monomers, aromatic vinyl monomers, vinylamine-based monomers, vinylamide-based monomers, acid group-containing monomers, (meth)acrylic acid derivatives, (meth)acrylic acid ester monomers, (meth)acrylamide monomers, (meth)acrylonitrile monomers, fluorine-containing (meth)acrylate monomers, maleimide, maleimide derivatives, diene-based monomers, and combinations thereof, and wherein the degree of swelling is measured using a solution which is obtained by dissolving LiPF 6 into a mixture solvent of ethylene carbonate, diethyl carbonate and vinylene carbonate in a mixing ratio of 68.5/30/1.5 by volume at a concentration of 1 mol/L, and a volume-average particle diameter of the organic particles is 0.80 to 1.50 times a volume-average particle diameter of the non-conductive inorganic particles, the volume-average particle diameter being measured in compliance with JIS Z8825 and representing a particle diameter where the cumulative volume from the fine side amounts to 50% of the entire volume in a particle size distribution (volume basis) measured by laser diffraction. non-conductive inorganic particles; and organic particles, wherein a difference in density between the non-conductive inorganic particles and the organic particles (non-conductive inorganic particles' density - organic particles' density) is 1.5 g/cm 3 or more, the density being a true density as measured by the gas displacement method, the content of the organic particles is 1 part by mass to 20 parts by mass per 100 parts by mass of the non-conductive inorganic particles, at least a surface layer portion of the organic particles is made of polymer having a degree of swelling in electrolysis solution of greater than 1 time to 4 times and having a glass-transition temperature measured in compliance with JIS K7121 of 50°C or above, wherein the polymer is made of monomers selected from the group consisting of vinyl chloride-based monomers, vinyl acetate-based monomers, aromatic vinyl monomers, vinylamine-based monomers, vinylamide-based monomers, acid group-containing monomers, (meth)acrylic acid derivatives, (meth)acrylic acid ester monomers, (meth)acrylamide monomers, (meth)acrylonitrile monomers, fluorine-containing (meth)acrylate monomers, maleimide, maleimide derivatives, diene-based monomers, and combinations thereof, and wherein the degree of swelling is measured using a solution which is obtained by dissolving LiPF 6 into a mixture solvent of ethylene carbonate, diethyl carbonate and vinylene carbonate in a mixing ratio of 68.5/30/1.5 by volume at a concentration of 1 mol/L, and a volume-average particle diameter of the organic particles is 0.80 to 1.50 times a volume-average particle diameter of the non-conductive inorganic particles, the volume-average particle diameter being measured in compliance with JIS Z8825 and representing a particle diameter where the cumulative volume from the fine side amounts to 50% of the entire volume in a particle size distribution (volume basis) measured by laser diffraction.