TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Composition: The component (B) is a thiol compound containing aromatic ring(s), and/or linear or branched 2-20C alicyclic carbon chain(s) in a molecule. The thiol compound is aliphatic thiol having sulfur or non-aromatic ring containing thiol, aromatic thiol, aromatic thiol having sulfur, and/or aliphatic thiol, preferably diethane(ethylene dithio)thiol, dimercapto benzene, bis(mercapto methyl)benzene, naphthalene dithiol, benzene trithiol, thiobis benzene thiol, trimethylol-propane tris(3-mercapto propionate), and/or pentaerythritol tetrakis(3-mercapto propionate), more preferably dimercapto benzene, bis(mercapto methyl)benzene, benzene trithiol, naphthalene dithiol, and/or thiobis benzene thiol. The alkenyl compound contains vinyl group or allyl group as alkenyl group. The alkenyl compound is aromatic alkenyl compound containing oxygen, sulfur, or silicon, aromatic alkenyl compound, aliphatic alkenyl compound, and/or aliphatic alkenyl compound containing sulfur, silicon or non-aromatic ring containing alkenyl compound, preferably divinylbenzene, diallyl benzene, trivinyl benzene, tetraallyl benzene, hexa allyl benzene, divinyl toluene, bisphenol A diallyl ether, diallyl oxybenzene, terephthalic-acid diallyl, diallyl phthalate, diallyl isophthalate, diallyl trimellitate, triaryl trimellitate, triaryl pyromellitate, tetraallyl pyromellitate, bis(dimethyl vinylsilyl)benzene, divinyl methylphenyl silane, divinyl di phenyl silane, and/or diaryl-diphenyl silane. The alkenyl compound contains benzene ring as an aromatic ring. The alkenyl compound is obtained by performing chain extension of alkenyl-group containing organic compound by hydrosilylation reaction using an organic compound. The organic compound is an organic compound having at least two hydrosilyl groups, organic compound having at least two alkenyl groups, and/or organic compound having at least two thiol groups. The alkenyl compound is reaction material of bis(dimethyl silyl)benzene and diallyl phthalate in molar ratio of 1:2-1:1, reaction material of bis(dimethyl silyl)benzene and divinylbenzene in molar ratio of 1:2-1:1, reaction material of diphenylsilane and diallyl phthalate in molar ratio of 1:2-1:1, reaction material of tetramethyl disiloxane and diaryl-dicarbonate in molar ratio of 1:2-1:1, reaction material of thiobis benzene thiol and diallyl phthalate in molar ratio of 1:2-1:1, reaction material of benzenedithiol and adipic acid divinyl ester in molar ratio of 1:2-1:1, reaction material of bis(mercapto methyl)benzene and diallyl phthalate in molar ratio of 1:2-1:1, reaction material of benzenedithiol and diaryl-dicarbonate in molar ratio of 1:2-1:1, reaction material of bis(mercapto ethylthio)ethane and nonadiene in molar ratio of 1:2-1:1, reaction material of thiobis benzene thiol and nonadiene in molar ratio of 1:2-1:1, reaction material of bis(dimethyl silyl)benzene and adipic acid divinyl ester in molar ratio of 1:2-1:1, reaction material of thiobis benzene thiol and divinylbenzene in molar ratio of 1:2-1:1, reaction material of thiobis benzene thiol and diaryl-di carbonate in molar ratio of 1:2-1:1, and/or reaction material of thiobis benzene thiol and adipic acid divinyl ester in molar ratio of 1:2-1:1. The curable composition further contains a thiol compound (D) having at least two thiol groups in a molecule or aromatic ring(s) and/or 3C or more carbon chain or non-aromatic ring in a molecule. The thiol compound contains benzene ring as an aromatic ring. The thiol compound (D) is reaction material of thiobis benzene thiol and diallyl phthalate in molar ratio of 2:1-1:1, reaction material of benzenedithiol and adipic acid divinyl in molar ratio of 2:1-1:1, reaction material of benzenedithiol and diallyl phthalate in molar ratio of 2:1-1:1, reaction material of bis(mercapto methyl)benzene and diallyl phthalate, reaction material of benzenedithiol and diaryl-dicarbonate in molar ratio of 2:1-1:1, reaction material of naphthalene dithiol and diallyl phthalate in molar ratio of 2:1-1:1, reaction material of bis(mercapto methyl)benzene and nonadiene in molar ratio of 2:1-1:1, reaction material of thiobis benzene thiol and nonadiene in molar ratio of 2:1-1:1, reaction material of thiobis benzene thiol and adipic acid divinyl in molar ratio of 2:1-1:1, and/or reaction material of diethane(ethylene dithio)thiol and trimethylol-propane triaryl ether in molar ratio of 3:1-3:2. The titanoxane compound is of formula: Ti( alpha )O( beta )(OR)( gamma ) (I). The content of titanoxane compound is 50-95 weight% with respect to total content of components (A, B and C).R=1-12C alkyl;( alpha )=2-80;( beta )=1.8( alpha ) to ( alpha );and( gamma )=4( alpha )-2( beta ).Preferred Properties: The molecular weight of the thiol compound (D) is 200-20000. The thiol group equivalent of thiol compound is 1000 g/eq or less.