A curable re-release adhesive which, when subjected to a curing reaction caused by irradiation with radiation, shows a sufficient drop of adhesion and causes the adherend to be warped to a minimized extent as developed by the shrinkage force caused by the curing reaction. The re-release adhesive contains a radiation-reactive polymer including a main chain and a plurality of intramolecular side chains, each such side chain having a terminal carbon-carbon double bond, a chain length of 6 or more in terms of number of atoms, and the same or a different number of atoms as each other side chain in the polymer. The release adhesive shows a shrinkage force of 30 MPa or less as developed by a curing reaction upon irradiation. A re-release adhesive sheet is also disclosed, including a substrate film and an adhesive layer containing the re-release adhesive, provided on one surface thereof.