A composite comprising a sheet layer and one of a curable resin layer or a film layer formed on one or both surfaces of the sheet layer, the sheet layer containing as a main component fine fibers with an average fiber width of 2 to 100 nm, wherein the fine fibers are cellulose fine fibers, wherein the sheet layer is a nonwoven fabric, and the sheet layer comprises a hydrophilic polymer selected from the group consisting of polyethylene glycol; cellulose derivatives such as hydroxyethylcellulose, carboxyethyl cellulose, and carboxymethyl cellulose; casein; dextrin; starch; modified starch; polyvinyl alcohol; modified polyvinyl alcohol such as acetoacetylated polyvinyl alcohol; polyethylene oxide; polyvinyl pyrrolidone; polyvinyl methyl ether, polyacrylates; polyacrylamide; acrylic alkyl ester copolymer; and urethane-based copolymer; or a hydrophilic low-molecular weight compound selected from the group consisting of glycerin, erythritol, xylitol, sorbitol, galactitol, mannitol, ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol, and butylene glycol, wherein the cellulose fine fibers are obtained by subjecting a cellulose raw material to chemical treatment and refining treatment, wherein the chemical treatment is one of ozonation treatment, TEMPO oxidation treatment, enzymatic treatment, and treatment with a compound that can form a covalent bond with the functional group in cellulose or fiber raw materials, wherein said compound is quaternary ammonium group-containing compound, carboxylic acid-based compound, or at least one compound selected from the group consisting of an oxoacid, polyoxoacid and salts thereof that have phosphorous atoms in the structure, wherein the content of the fine fibers in the sheet layer with respect to the dry weight of the sheet layer is greater than or equal to 50 mass%; wherein a density of the sheet layer is greater than or equal to 0.90 g/cm 3 and is less than or equal to 1.60 g/cm 3; wherein the one of the curable resin layer or the film layer is laminated on the one or both surfaces of the sheet layer with a covering layer interposed therebetween, the covering layer being provided on one or both surfaces of the sheet layer, wherein the covering layer is a hybrid material of an organic component and an inorganic component; the organic component is at least one component selected from the group consisting of a methyl group, a mercapto group, a methacryl group, an acryloyl group, a vinyl group, and an amino group; and the hybrid material of the organic compound and the inorganic compound is silsesquioxane; or wherein the covering layer contains at least one type of resin selected from the group consisting of heat-curable resin, thermoplastic resin, and photo-curable resin; such as polyester resin, urethane resin, acrylic resin, olefin resin, fluorine resin, vinyl chloride resin, styrene resin, epoxy resin, and silicone resin. wherein the sheet layer is a nonwoven fabric, and the sheet layer comprises a hydrophilic polymer selected from the group consisting of polyethylene glycol; cellulose derivatives such as hydroxyethylcellulose, carboxyethyl cellulose, and carboxymethyl cellulose; casein; dextrin; starch; modified starch; polyvinyl alcohol; modified polyvinyl alcohol such as acetoacetylated polyvinyl alcohol; polyethylene oxide; polyvinyl pyrrolidone; polyvinyl methyl ether, polyacrylates; polyacrylamide; acrylic alkyl ester copolymer; and urethane-based copolymer; or a hydrophilic low-molecular weight compound selected from the group consisting of glycerin, erythritol, xylitol, sorbitol, galactitol, mannitol, ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol, and butylene glycol, wherein the cellulose fine fibers are obtained by subjecting a cellulose raw material to chemical treatment and refining treatment, wherein the chemical treatment is one of ozonation treatment, TEMPO oxidation treatment, enzymatic treatment, and treatment with a compound that can form a covalent bond with the functional group in cellulose or fiber raw materials, wherein said compound is quaternary ammonium group-containing compound, carboxylic acid-based compound, or at least one compound selected from the group consisting of an oxoacid, polyoxoacid and salts thereof that have phosphorous atoms in the structure, wherein the content of the fine fibers in the sheet layer with respect to the dry weight of the sheet layer is greater than or equal to 50 mass%; wherein a density of the sheet layer is greater than or equal to 0.90 g/cm 3 and is less than or equal to 1.60 g/cm 3; wherein the one of the curable resin layer or the film layer is laminated on the one or both surfaces of the sheet layer with a covering layer interposed therebetween, the covering layer being provided on one or both surfaces of the sheet layer, wherein the covering layer is a hybrid material of an organic component and an inorganic component; the organic component is at least one component selected from the group consisting of a methyl group, a mercapto group, a methacryl group, an acryloyl group, a vinyl group, and an amino group; and the hybrid material of the organic compound and the inorganic compound is silsesquioxane; or wherein the covering layer contains at least one type of resin selected from the group consisting of heat-curable resin, thermoplastic resin, and photo-curable resin; such as polyester resin, urethane resin, acrylic resin, olefin resin, fluorine resin, vinyl chloride resin, styrene resin, epoxy resin, and silicone resin.