A condensation curable resin composition comprising: 100 parts by weight of a silphenylene skeleton-bearing organosilicon compound containing at least two hydroxyl and/or alkoxy groups per molecule, represented by the general formula: (R 1 3 SiO 0.5) a (R 1 2 SiO) b (R 2 SiO 1.5) c (SiO 2) d Z e (O 0.5 X) f wherein R 1 is independently hydrogen or a C 1 -C 12 unsubstituted monovalent hydrocarbon group, R 2 is independently a C 1 -C 12 unsubstituted monovalent hydrocarbon group, Z is independently a group having the formula: wherein R 3 is independently a C 1 -C 12 unsubstituted monovalent hydrocarbon group, and n is an integer of 0 to 3, X is independently hydrogen or a C 1 -C 6 unsubstituted monovalent hydrocarbon group, a is an integer of 0 to 500, b is an integer of 0 to 5,000, c is an integer of 0 to 500, d is an integer of 0 to 500, e is an integer of 1 to 500, f is an integer of 2 to 100, and a+b+c+d+e is an integer of 1 to 5,001, and 0.1 to 200 parts by weight of an organosilicon compound having a hydrogen atom and a hydroxyl and/or alkoxy group on a common silicon atom, represented by the general formula: (R 1 3 SiO 0.5) a' (R 4 2 SiO) b' (R 2 SiO 1.5) c' (SiO 2) d' Z e' (O 0.5 X) f' (R 1 k HSi 2-k O 0.5) g' wherein R 1, R 2, Z and X are as defined above, R 4 is hydrogen, a C 1 -C 12 unsubstituted monovalent hydrocarbon group or OX, a' is an integer of 0 to 500, b' is an integer of 0 to 5,000, c' is an integer of 0 to 500, d' is an integer of 0 to 500, e' is an integer of 0 to 500, f' is an integer of 0 to 100, g' is an integer of 2 to 100, k is 0 or 1, and a'+b'+c'+d'+e'+g' is an integer of 2 to 5,002, the composition being free of a condensation catalyst. 100 parts by weight of a silphenylene skeleton-bearing organosilicon compound containing at least two hydroxyl and/or alkoxy groups per molecule, represented by the general formula: (R 1 3 SiO 0.5) a (R 1 2 SiO) b (R 2 SiO 1.5) c (SiO 2) d Z e (O 0.5 X) f wherein R 1 is independently hydrogen or a C 1 -C 12 unsubstituted monovalent hydrocarbon group, R 2 is independently a C 1 -C 12 unsubstituted monovalent hydrocarbon group, Z is independently a group having the formula: wherein R 3 is independently a C 1 -C 12 unsubstituted monovalent hydrocarbon group, and n is an integer of 0 to 3, X is independently hydrogen or a C 1 -C 6 unsubstituted monovalent hydrocarbon group, a is an integer of 0 to 500, b is an integer of 0 to 5,000, c is an integer of 0 to 500, d is an integer of 0 to 500, e is an integer of 1 to 500, f is an integer of 2 to 100, and a+b+c+d+e is an integer of 1 to 5,001, and 0.1 to 200 parts by weight of an organosilicon compound having a hydrogen atom and a hydroxyl and/or alkoxy group on a common silicon atom, represented by the general formula: (R 1 3 SiO 0.5) a' (R 4 2 SiO) b' (R 2 SiO 1.5) c' (SiO 2) d' Z e' (O 0.5 X) f' (R 1 k HSi 2-k O 0.5) g' wherein R 1, R 2, Z and X are as defined above, R 4 is hydrogen, a C 1 -C 12 unsubstituted monovalent hydrocarbon group or OX, a' is an integer of 0 to 500, b' is an integer of 0 to 5,000, c' is an integer of 0 to 500, d' is an integer of 0 to 500, e' is an integer of 0 to 500, f' is an integer of 0 to 100, g' is an integer of 2 to 100, k is 0 or 1, and a'+b'+c'+d'+e'+g' is an integer of 2 to 5,002,