An aqueous dispersion type pressure-sensitive adhesive composition which has a small increase of a peel force to a release liner having a silicone release agent applied thereto or back coating layer, and pressure-sensitive adhesive sheets comprising the composition. The aqueous dispersion type pressure-sensitive adhesive composition comprises an aqueous dispersion of a polymer obtained by copolymerizing a monomer mixture comprising one or more alkyl (meth)acrylates as the main component and at least one silane monomer, and an organic compound capable of bonding to the silane monomer.