A room-temperature-curable organopolysiloxane composition for an oil seal comprising: 100 parts by weight of a diorganopolysiloxane having one hydroxyl group and/or one hydrolyzable silyl group bonded to a silicon atom at both ends of the molecular chain and having a viscosity at 23°C of 20 to 1,000,000 mPa·s; 1 to 500 parts by weight of an inorganic filler; 0.1 to 40 parts by weight of a hydrolyzable organosilane compound and/or a partial hydrolytic condensate thereof, the hydrolyzable organosilane compound having the general formula below: wherein R 1 is each independently an unsubstituted or substituted monovalent hydrocarbon group having 1 to 12 carbon atoms, R 2 is an unsubstituted or substituted monovalent hydrocarbon group having 1 to 12 carbon atoms, Y is a hydrolyzable group, and n is 0, 1, or 2; 0.01 to 5 parts by weight of a silane coupling agent and/or a partial hydrolytic condensate thereof, the silane coupling agent having the general formula below: R 5 R 4 a SiX 3-a wherein R 3 is a monovalent hydrocarbon group having 1 to 20 carbon atoms and having at least one functional group containing any one or more atoms selected from a nitrogen atom, a sulfur atom, and an oxygen atom, R 4 is an unsubstituted or substituted monovalent hydrocarbon group having 1 to 10 carbon atoms, X is a hydrolyzable group, and a is 0, 1, or 2; and 0.1 to 5 parts by weight of a curing catalyst consisting of one, or two or more selected from a non-silicon-based organic compound, a hydrolyzable organosilane compound, and a partial hydrolytic condensate thereof, other than the components and, having at least one guanidine skeleton in one molecule, the guanidine skeleton having the general formula below: wherein R 5 is each independently a hydrogen atom, an unsubstituted or substituted monovalent hydrocarbon group having 1 to 20 carbon atoms, a methylol group, or a cyano group. 100 parts by weight of a diorganopolysiloxane having one hydroxyl group and/or one hydrolyzable silyl group bonded to a silicon atom at both ends of the molecular chain and having a viscosity at 23°C of 20 to 1,000,000 mPa·s; 1 to 500 parts by weight of an inorganic filler; 0.1 to 40 parts by weight of a hydrolyzable organosilane compound and/or a partial hydrolytic condensate thereof, the hydrolyzable organosilane compound having the general formula below: wherein R 1 is each independently an unsubstituted or substituted monovalent hydrocarbon group having 1 to 12 carbon atoms, R 2 is an unsubstituted or substituted monovalent hydrocarbon group having 1 to 12 carbon atoms, Y is a hydrolyzable group, and n is 0, 1, or 2; 0.01 to 5 parts by weight of a silane coupling agent and/or a partial hydrolytic condensate thereof, the silane coupling agent having the general formula below: R 5 R 4 a SiX 3-a wherein R 3 is a monovalent hydrocarbon group having 1 to 20 carbon atoms and having at least one functional group containing any one or more atoms selected from a nitrogen atom, a sulfur atom, and an oxygen atom, R 4 is an unsubstituted or substituted monovalent hydrocarbon group having 1 to 10 carbon atoms, X is a hydrolyzable group, and a is 0, 1, or 2; and 0.1 to 5 parts by weight of a curing catalyst consisting of one, or two or more selected from a non-silicon-based organic compound, a hydrolyzable organosilane compound, and a partial hydrolytic condensate thereof, other than the components and, having at least one guanidine skeleton in one molecule, the guanidine skeleton having the general formula below: wherein R 5 is each independently a hydrogen atom, an unsubstituted or substituted monovalent hydrocarbon group having 1 to 20 carbon atoms, a methylol group, or a cyano group.