Provided is a curable composition which can easily regulate the properties of a cured object prepared therefrom, which can prepare a cured object that does not substantially discolor or soften a finishing agent or coating material applied to the surface thereof, and which has a high curing rate in the inner regions. The curable composition contains (A) a polymer having at least one mercapto group at the molecular ends, the polymer being derived from a thiocarbonylthio group-containing polymer (a2) prepared by polymerizing a monomer (a1) which contains an acrylic ester as a principal component and which contains 50% by weight or more of the acrylic ester and less than 50% by weight of a monomer copolymerizable with the acrylic ester in the presence of a thiocarbonylthio group-containing compound; (B) a compound having at least two mercapto groups per molecule; and (C) an oxidizing agent.