Abstract: A shape-memory polyester prepolymer is prepared with at least one kind of dicarboxylic acid component and at least one kind of diol, triol or polyol component in such a way to have unsaturated end group, wherein the dicarboxylic acid component comprises aromatic dicarboxylic acid in an amount of not less than 80% by mole based on the total mole of the dicarboxylic acid component; the diol component comprises a diol containing 2-10 carbon atoms in an amount of not less than 80% by mole based on the total mole of the diol component; a repeating unit of the ester bond ranging in number from 2 to 50; and the end group has crosslinkable, ethylenically unsaturated bond. The prepolymer shows particularly excellent heat resistance and excellent chemical resistance and also exhibits excellent transparency.