A laminated polyester film for optical applications, comprising: a readily-adhesive polyester film for optical applications comprising: a biaxially-stretched polyester film; and a coating layer that is stacked on at least one side of the polyester film and produced by a process comprising: applying, to at least one side of the polyester film, an aqueous coating liquid containing a resin composition comprising an aqueous polyester resin and at least one of a water-soluble titanium chelate compound, a water-soluble titanium acylate compound, a water-soluble zirconium chelate compound, or a water soluble zirconium acylate compound as main components, wherein "water-soluble" means that the compound can be dissolved in water or in an aqueous solution containing less than 50% by mass of a water-soluble organic solvent, and wherein the mixing ratio / is from 10/90 to 95/5 by mass; drying the coating; and then stretching the coating in at least one direction; and a hard coating layer that is stacked on the coating layer on at least one side of the readily-adhesive polyester film and comprises an electron beam-cured or ultraviolet light-cured acrylic resin or a heat-cured siloxane resin. a readily-adhesive polyester film for optical applications comprising: a biaxially-stretched polyester film; and a coating layer that is stacked on at least one side of the polyester film and produced by a process comprising: applying, to at least one side of the polyester film, an aqueous coating liquid containing a resin composition comprising an aqueous polyester resin and at least one of a water-soluble titanium chelate compound, a water-soluble titanium acylate compound, a water-soluble zirconium chelate compound, or a water soluble zirconium acylate compound as main components, wherein "water-soluble" means that the compound can be dissolved in water or in an aqueous solution containing less than 50% by mass of a water-soluble organic solvent, and wherein the mixing ratio / is from 10/90 to 95/5 by mass; drying the coating; and then stretching the coating in at least one direction; and a hard coating layer that is stacked on the coating layer on at least one side of the readily-adhesive polyester film and comprises an electron beam-cured or ultraviolet light-cured acrylic resin or a heat-cured siloxane resin. a biaxially-stretched polyester film; and a coating layer that is stacked on at least one side of the polyester film and produced by a process comprising: applying, to at least one side of the polyester film, an aqueous coating liquid containing a resin composition comprising an aqueous polyester resin and at least one of a water-soluble titanium chelate compound, a water-soluble titanium acylate compound, a water-soluble zirconium chelate compound, or a water soluble zirconium acylate compound as main components, wherein "water-soluble" means that the compound can be dissolved in water or in an aqueous solution containing less than 50% by mass of a water-soluble organic solvent, and wherein the mixing ratio / is from 10/90 to 95/5 by mass; drying the coating; and then stretching the coating in at least one direction; and a hard coating layer that is stacked on the coating layer on at least one side of the readily-adhesive polyester film and comprises an electron beam-cured or ultraviolet light-cured acrylic resin or a heat-cured siloxane resin.