A curable composition comprising: an organic polymer having a silicon-containing group which is capable of crosslinking by forming siloxane bonds and is represented by the general formula: -SiR 1 X 2 wherein R 1 represents any of an alkyl group having 1 to 20 carbon atoms, an aryl group having 6 to 20 carbon atoms, an aralkyl group having 7 to 20 carbon atoms or a triorganosiloxy group represented by (R') 3 SiO- where R' is a hydrocarbon group having 1 to 20 carbon atoms and three R's may be the same or different, X represents hydroxyl group or a hydrolyzable group and two Xs may be the same or different, wherein a main chain skeleton of said organic polymer is at least one selected from the group consisting of polyoxyalkylene polymers, saturated hydrocarbon polymers and (meth)acrylate polymers, one or more kinds selected from a titanium catalyst, an aluminum catalyst and a zirconium catalyst and a low molecular weight compound containing a hydrolyzable silicon group and having a molecular weight of from 100 to 1,000, characterized in that a ratio (a/b) of the total mole (a) of titanium atoms, aluminum atoms and zirconium atoms of the component in the composition to the total mole (b) of silicon atoms of the component in the composition is more than 0.4, and where said low molecular weight compound containing a hydrolysable silicon group can be used alone or in combinations of two or more. an organic polymer having a silicon-containing group which is capable of crosslinking by forming siloxane bonds and is represented by the general formula: -SiR 1 X 2 wherein R 1 represents any of an alkyl group having 1 to 20 carbon atoms, an aryl group having 6 to 20 carbon atoms, an aralkyl group having 7 to 20 carbon atoms or a triorganosiloxy group represented by (R') 3 SiO- where R' is a hydrocarbon group having 1 to 20 carbon atoms and three R's may be the same or different, X represents hydroxyl group or a hydrolyzable group and two Xs may be the same or different, wherein a main chain skeleton of said organic polymer is at least one selected from the group consisting of polyoxyalkylene polymers, saturated hydrocarbon polymers and (meth)acrylate polymers, wherein R 1 represents any of an alkyl group having 1 to 20 carbon atoms, an aryl group having 6 to 20 carbon atoms, an aralkyl group having 7 to 20 carbon atoms or a triorganosiloxy group represented by (R') 3 SiO- where R' is a hydrocarbon group having 1 to 20 carbon atoms and three R's may be the same or different, X represents hydroxyl group or a hydrolyzable group and two Xs may be the same or different, wherein a main chain skeleton of said organic polymer is at least one selected from the group consisting of polyoxyalkylene polymers, saturated hydrocarbon polymers and (meth)acrylate polymers, one or more kinds selected from a titanium catalyst, an aluminum catalyst and a zirconium catalyst and a low molecular weight compound containing a hydrolyzable silicon group and having a molecular weight of from 100 to 1,000, characterized in that a ratio (a/b) of the total mole (a) of titanium atoms, aluminum atoms and zirconium atoms of the component in the composition to the total mole (b) of silicon atoms of the component in the composition is more than 0.4, and where said low molecular weight compound containing a hydrolysable silicon group can be used alone or in combinations of two or more.