A surface-protecting pressure-sensitive adhesive sheet includes: a substrate; and a pressure-sensitive adhesive layer that is provided on at least one side of the substrate and made from a polyester-based pressure-sensitive adhesive composition containing a crosslinking agent and a polyester including at least a lactic acid unit, a dibasic acid unit, and a glycol unit. The dibasic acid unit includes a dimer acid, the polyester has a weight average molecular weight of 20,000 to 200,000 and a glass transition temperature of −70 to −20° C. as measured using a differential scanning calorimeter at a temperature rise rate of 20° C./minute, the polyester-based pressure-sensitive adhesive composition has a hydroxyl value of 20 to 60 mgKOH/g, and the pressure-sensitive adhesive layer has a gel fraction of 85 to 99% by weight.