NOVELTY - A polyester composition comprises polyester A, 1.5-3 wt.% carbon black with respect to polyester whole composition, 0.59-11.15 mol/t metallic element consisting of manganese (Mn), calcium (Ca), and aluminum (Al) with respect to polyester whole composition, elemental phosphorus (P), and alkali metal.    USE - A polyester composition for polyester film manufacture (claimed) used for solar cell back sheet, electrical insulation material for water heater motors, capacitor material, motor vehicle material, and building material.    ADVANTAGE - Polyester composition and polyester film has high heat-and-moisture resistance over long a term and excellent concealability.    DETAILED DESCRIPTION - A polyester composition comprises polyester A, 1.5-3 wt.% carbon black with respect to polyester whole composition, 0.59-11.15 mol/t metallic element consisting of manganese (Mn), calcium (Ca), and aluminum (Al) with respect to polyester whole composition, elemental phosphorus (P), and alkali metal. Elemental phosphorus satisfies equation M/P=0.8-2 (i) in which M=0.5x M1+M2+1.5x M3, wherein M1 is content (mol/t) of alkali metal, M2 is total (mol/t) of elemental Mn content (mol/t) and elemental Ca content (mol/t), M3 is elemental Al content (mol/t), and P is elemental phosphorus content (mol/t) with respect to polyester whole composition. INDEPENDENT CLAIMS are included for:    (1) polyester film containing polyester composition; and    (2) manufacture of polyester composition which involves adding manganese acetate and/or calcium acetate to carboxylic component (a1) which has greater than or equal to 2 carboxylic acid groups and alcohol component (a2) which has greater than or equal to 2 hydroxyl groups, reacting components (a1) and (a2), obtaining ester composition alpha 1 which has ester compound (A1) and Mn ion and/or Ca ion, adding phosphoric acid to ester composition alpha 1, polymerizing component (A1), obtaining polyester composition alpha which has polyester A, phosphoric acid, and Mn ion and/or Ca ion, adding carbon black to polyester composition alpha to obtain polyester composition beta , and using polyester composition beta to obtain polyester composition.