The present invention provides a curable composition which has a high recovery ratio, a high creep resistance, a practical curability and a storage stability. The present invention relates to a curable composition comprising a reactive silicon group-containing organic polymer (A) and a carboxylic acid (B), (I) wherein the composition comprises, as the carboxylic acid (B), a carboxylic acid (C) in which the carbon atom adjacent to the carbonyl group is a quaternary carbon atom; and/or (II) wherein the composition comprises a metal carboxylate (D) formed between a carboxylic acid in which the carbon atom adjacent to the carbonyl group is a quaternary carbon atom and a metal atom of 208 or less in atomic weight.