A polyester-based pressure-sensitive adhesive composition comprises a polyester obtained by condensation polymerization of at least a dicarboxylic acid having a side chain and a diol, a polyether polyol, and a crosslinking agent, wherein the polyester has a weight average molecular weight of 5000 to 50000, the polyether polyol contains a polyether polyol having hydroxyl groups at only part of terminals and/or all terminals, the polyether polyol having hydroxyl groups at only part of terminals has a number average molecular weight of 100 to 1500, and the polyether polyol having hydroxyl groups at only part of terminals is contained in an amount of 1 to 35 parts by weight based on 100 parts by weight of the polyester.