The present invention relates to a pressure-sensitive adhesive sheet, which includes: a base material including a foamed substance; and a pressure-sensitive adhesive layer disposed on at least one surface of the base material, in which the pressure-sensitive adhesive layer is formed by a water-dispersible acrylic pressure-sensitive adhesive composition containing a water-dispersible acrylic copolymer (a) having a weight-average molecular weight of from 400,000 to 900,000, said copolymer containing a (meth)acrylic acid alkyl ester having 2 to 14 carbon atoms in the alkyl group thereof as a principal monomer component and a functional group-containing monomer as a monomer component; and a water-dispersible acrylic low-molecular weight component (b) having a weight-average molecular weight of from 5,000 to 250,000. According to the pressure-sensitive adhesive sheet, a pressure-sensitive adhesive layer is formed with an excellent adhesivity on a base material foamed by a foamed substance, without restriction in the method of forming the pressure-sensitive adhesive layer or in the type of a crosslinking agent.