An object of the present invention is to provide a curing composition which is practically curable and highly adhesive even though a non-organotin compound is included as a curing catalyst. Problems involved are solved by a curing composition characterized by including (A) an organic polymer having one or more silicon-containing groups capable of cross linking by forming siloxane bonds, (B) a metal carboxylate and/or carboxylic acid, and (C) a silicon compound having a hetero atom on the carbon atom in the .alpha. or .beta. position with respect to the silicon atom.