Provided are a polyester-based pressure-sensitive adhesive composition having high wetting ability and superior adherability and light peelability, and a pressure-sensitive adhesive sheet produced with such a pressure-sensitive adhesive composition. The polyester-based pressure-sensitive adhesive composition includes a polyester obtained by polycondensation of a difunctional or polyfunctional carboxylic acid and a diol; a fatty acid ester; and a crosslinking agent, wherein the polyester has a weight average molecular weight of 8,500 to 50,000, and the fatty acid ester has no additional functional group and has a molecular weight of 200 to 700. The polyester-based pressure-sensitive adhesive composition contains 10 to 150 parts by weight of the fatty acid ester based on 100 parts by weight of the polyester.