A room-temperature-curable polyorganosiloxane composition comprising: 100 parts by mass of polyorganosiloxane containing, 10 to 80 parts by mass of a polyorganosiloxane having the both molecular ends blocked with an alkoxysilyl group, which is expressed by a general formula, where R 1 is an alkyl group or an alkoxy-substituted alkyl group being an alkyl group in which part of hydrogen atoms is substituted by an alkoxy group, R 2 and R 3 are each an unsubstituted monovalent hydrocarbon group or a monovalent hydrocarbon group in which part of hydrogen atoms is substituted by a halogen atom or a cyano-alkyl group, X is bivalent oxygen, i.e. an oxy group, or a bivalent hydrocarbon group, "a" is 0 or 1, and "n" is an integer expressed by 1 ≤ n < 20, and 90 to 20 parts by mass of a partial hydrolysis condensate (the number of Si atoms in one molecule is 10 to 200) of a silane compound expressed by a general formula, R 4 b Si(OR 5) 4-b.... where R 4 is an unsubstituted monovalent hydrocarbon group or a monovalent hydrocarbon group in which part of hydrogen atoms is substituted by a halogen atom or a cyano-alkyl group, R 5 is an alkyl group or an alkoxy-substituted alkyl group being an alkyl group in which part of hydrogen atoms is substituted by an alkoxy group, "b"is 0, 1, or 2 and an average value of "b" is 0.8 to 1.2; 0.1 to 15 parts by mass of a silane compound expressed by a general formula or a partial hydrolysis condensate (the number of Si atoms in one molecule is 1 or more and less than 10) of the silane compound, R 6 c Si(OR 7) 4-c... where R 6 is an unsubstituted monovalent hydrocarbon group or a monovalent hydrocarbon group in which part of hydrogen atoms is substituted by a halogen atom or a cyano-alkyl group, R 7 is an alkyl group or an alkoxy-substituted alkyl group being an alkyl group in which part of hydrogen atoms is substituted by an alkoxy group, and "c" is 0, 1, or 2; and 0.1 to 15 parts by mass of an organic titanium compound as a curing catalyst. 100 parts by mass of polyorganosiloxane containing, 10 to 80 parts by mass of a polyorganosiloxane having the both molecular ends blocked with an alkoxysilyl group, which is expressed by a general formula, where R 1 is an alkyl group or an alkoxy-substituted alkyl group being an alkyl group in which part of hydrogen atoms is substituted by an alkoxy group, R 2 and R 3 are each an unsubstituted monovalent hydrocarbon group or a monovalent hydrocarbon group in which part of hydrogen atoms is substituted by a halogen atom or a cyano-alkyl group, X is bivalent oxygen, i.e. an oxy group, or a bivalent hydrocarbon group, "a" is 0 or 1, and "n" is an integer expressed by 1 ≤ n < 20, and 90 to 20 parts by mass of a partial hydrolysis condensate (the number of Si atoms in one molecule is 10 to 200) of a silane compound expressed by a general formula, R 4 b Si(OR 5) 4-b.... where R 4 is an unsubstituted monovalent hydrocarbon group or a monovalent hydrocarbon group in which part of hydrogen atoms is substituted by a halogen atom or a cyano-alkyl group, R 5 is an alkyl group or an alkoxy-substituted alkyl group being an alkyl group in which part of hydrogen atoms is substituted by an alkoxy group, "b"is 0, 1, or 2 and an average value of "b" is 0.8 to 1.2; 10 to 80 parts by mass of a polyorganosiloxane having the both molecular ends blocked with an alkoxysilyl group, which is expressed by a general formula, where R 1 is an alkyl group or an alkoxy-substituted alkyl group being an alkyl group in which part of hydrogen atoms is substituted by an alkoxy group, R 2 and R 3 are each an unsubstituted monovalent hydrocarbon group or a monovalent hydrocarbon group in which part of hydrogen atoms is substituted by a halogen atom or a cyano-alkyl group, X is bivalent oxygen, i.e. an oxy group, or a bivalent hydrocarbon group, "a" is 0 or 1, and "n" is an integer expressed by 1 ≤ n < 20, and 90 to 20 parts by mass of a partial hydrolysis condensate (the number of Si atoms in one molecule is 10 to 200) of a silane compound expressed by a general formula, R 4 b Si(OR 5) 4-b.... where R 4 is an unsubstituted monovalent hydrocarbon group or a monovalent hydrocarbon group in which part of hydrogen atoms is substituted by a halogen atom or a cyano-alkyl group, R 5 is an alkyl group or an alkoxy-substituted alkyl group being an alkyl group in which part of hydrogen atoms is substituted by an alkoxy group, "b"is 0, 1, or 2 and an average value of "b" is 0.8 to 1.2; 0.1 to 15 parts by mass of a silane compound expressed by a general formula or a partial hydrolysis condensate (the number of Si atoms in one molecule is 1 or more and less than 10) of the silane compound, R 6 c Si(OR 7) 4-c... where R 6 is an unsubstituted monovalent hydrocarbon group or a monovalent hydrocarbon group in which part of hydrogen atoms is substituted by a halogen atom or a cyano-alkyl group, R 7 is an alkyl group or an alkoxy-substituted alkyl group being an alkyl group in which part of hydrogen atoms is substituted by an alkoxy group, and "c" is 0, 1, or 2; and 0.1 to 15 parts by mass of an organic titanium compound as a curing catalyst.