A condensation curable resin composition comprising a silphenylene oligomer skeleton-bearing organosilicon compound having 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 1 SiO 1.5) c (SiO 2) d Z e (O 0.5 R 2) f wherein R 1 is independently hydrogen or a C 1 -C 12 unsubstituted monovalent hydrocarbon group free of aliphatic unsaturation, Z is independently a group having the formula: wherein R 3 is independently a C 1 -C 12 unsubstituted monovalent hydrocarbon group free of aliphatic unsaturation, and n is an integer of 1 to 3, R 2 is independently hydrogen or a C 1 -C 6 alkyl 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, and f is an integer of 2 to 100, wherein component comprises (A-i) a silphenylene oligomer skeleton-bearing branched organosilicon compound having at least two hydroxyl and/or alkoxy groups per molecule, represented by formula wherein b is an integer of 0 to 1,000, and 1 ≤ c+d ≤ 1,000, and wherein component comprises (A-ii) a silphenylene oligomer skeleton-bearing linear organosilicon compound having hydroxyl and/or alkoxy groups at both ends of the molecular chain, represented by the general formula: (R 1 2 SiO) b' Z e' (O 0.5 R 2) 2 wherein R 1, R 2 and Z are as defined above, b' is an integer of 0 to 5,000, e' is an integer of 1 to 500, and 1 ≤ b'+e' ≤ 5,001. wherein R 1 is independently hydrogen or a C 1 -C 12 unsubstituted monovalent hydrocarbon group free of aliphatic unsaturation, Z is independently a group having the formula: wherein R 3 is independently a C 1 -C 12 unsubstituted monovalent hydrocarbon group free of aliphatic unsaturation, and n is an integer of 1 to 3, R 2 is independently hydrogen or a C 1 -C 6 alkyl 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, and f is an integer of 2 to 100, wherein component comprises (A-i) a silphenylene oligomer skeleton-bearing branched organosilicon compound having at least two hydroxyl and/or alkoxy groups per molecule, represented by formula wherein b is an integer of 0 to 1,000, and 1 ≤ c+d ≤ 1,000, and wherein component comprises (A-ii) a silphenylene oligomer skeleton-bearing linear organosilicon compound having hydroxyl and/or alkoxy groups at both ends of the molecular chain, represented by the general formula: (R 1 2 SiO) b' Z e' (O 0.5 R 2) 2 wherein R 1, R 2 and Z are as defined above, b' is an integer of 0 to 5,000, e' is an integer of 1 to 500, and 1 ≤ b'+e' ≤ 5,001. wherein R 3 is independently a C 1 -C 12 unsubstituted monovalent hydrocarbon group free of aliphatic unsaturation, and n is an integer of 1 to 3, R 2 is independently hydrogen or a C 1 -C 6 alkyl 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, and f is an integer of 2 to 100, wherein component comprises (A-i) a silphenylene oligomer skeleton-bearing branched organosilicon compound having at least two hydroxyl and/or alkoxy groups per molecule, represented by formula wherein b is an integer of 0 to 1,000, and 1 ≤ c+d ≤ 1,000, and wherein component comprises (A-ii) a silphenylene oligomer skeleton-bearing linear organosilicon compound having hydroxyl and/or alkoxy groups at both ends of the molecular chain, represented by the general formula: (R 1 2 SiO) b' Z e' (O 0.5 R 2) 2 wherein R 1, R 2 and Z are as defined above, b' is an integer of 0 to 5,000, e' is an integer of 1 to 500, and 1 ≤ b'+e' ≤ 5,001.