PURPOSE: To obtain a polyester resin for coating having good blocking resistance, solvent resistance and hardness by depolymerizing a straight-chain polyester resin with tri- or more polyhydric alcohol and/or tri- or more valent hydroxycarboxylic acid.

CONSTITUTION: (A) 100 pts. wt. straight-chain polyester resin having ≥10000 number-average molecular weight and synthesized from A1: an acid component consisting of 100-30mol% aromatic dicarboxylic acid and 0-70mol% aliphatic dicarboxylic acid component based on total acid components and A2: an alcohol component consisting of a dialcohol is blended with (B) 0.02-0.18 pts.wt., preferably 0.02-0.1 pts. wt. tri- or more polyhydric alcohol (B1) (e.g. trimethylol propane) and/or tri or more valent hydroxy carboxylic acid (B2) having each one or more OH group and COOH group, with the proviso that total number of these groups is ≥3 (e.g. dimethylol propionic acid) and the blend is depolymerized under ordinary pressure, preferably at 200-300°C to produce a branched polyester resin for coating, preferably having 5000-20000 number- average molecular weight.