The present invention provides a polyester-based adhesive composition, as well as an adhesive sheet using the same, that can be manufactured even from plant-derived raw materials without the use of expensive silicone-based adhesives and the like, that has good wettability in relation to an adherend, that is easy to peel off (repeelable), that prevents increases in adhesive force (peeling force), that is stain-resistant (does not leave residual glue and the like), and that can be used in the manufacture of an adhesive sheet (particularly for surface-protecting applications) with outstanding workability. This polyester-based adhesive composition comprises at least a polyester obtained through polycondensation of dicarboxylic acid with a side chain and a diol, a polyether polyol, and a cross-linking agent, and is characterized in that the weight-average molecular weight of the polyester is between 5000 and 50,000; that the polyether polyol comprises polyether polyols with hydroxyl groups on only some terminal and/or all terminals; that the number average molecular weight of the polyether polyols with hydroxyl groups on only some terminals is between 100 and 1500; and that the polyether polyols with hydroxyl groups on only some terminals are present at 1 to 35 parts by weight relative to 100 parts by weight of the polyester.