The present invention relates to a polyester for thermal transfer image-receiving sheets which includes a polyester A produced from an alcohol component containing 50 mol % or more of an alkyleneoxide adduct of 2,2-bis(4-hydroxyphenyl)propane and an acid component containing 80 mol % or more of an aliphatic carboxylic acid and/or an alicyclic carboxylic acid as a total amount thereof, and a polyester B produced from an alcohol component containing 80 mol % or more of the alkyleneoxide adduct of 2,2-bis(4-hydroxyphenyl)propane and an acid component containing 10 to 35 mol % of a trivalent or higher valent aromatic polycarboxylic acid; a resin dispersion containing the polyester; a process for producing the resin dispersion; a thermal transfer image-receiving sheet using the polyester; and a process for producing the thermal transfer image-receiving sheet. The thermal transfer image-receiving sheet is capable of satisfying all of a dyeability, a light resistance and a releasability at the same time.