A thermally conductive silicone composition comprising: 100 parts by mass of an organopolysiloxane having a viscosity of at least 500 mPa.s at 25°C; 400 to 3,500 parts by mass of a thermally conductive filler; 0.1 to 10 parts by mass of a fine hydrophobized silica powder; an organopolysiloxane represented by the general formula given below and having a viscosity of less than 500 mPa-s at 25°C: R 1 3 SiO (R 1 2 SiO) m, (R 1 R 3 SiO) n R 1 2 Si-X-SiR 1 (3.a) (OR 2) a {wherein X represents an oxygen atom or a bivalent hydrocarbon group having 2 to 10 carbon atoms; R 1 represents identical or different monovalent hydrocarbon groups which are free of unsaturated aliphatic bonds; R 2 represents groups selected from alkyl groups, alkoxyalkyl groups, alkenyl groups, or acyl groups; R 3 is represented by the following general formula: -X-SiR 1 (3-b) (OR 2) b (wherein X, R 1, and R 2 are the same as defined above; and "b" is an integer ranging from 1 to 3); "a" is an integer ranging from 0 to 3; "m" is an integer equal to or greater than 0; and "n" is an integer equal to or greater than 0; however, when "a" is equal to 0, "n" is an integer equal to or greater than 1} (component is used in an amount of 0.005 to 10 parts by mass per 100 parts by mass of component); and a silane compound of the following general formula: R 4 (4-c) Si(OR 2) c (wherein R 4 is a group selected from a monovalent hydrocarbon group, epoxy- containing organic group, methacryl-containing organic group, or an acryl- containing organic group; R 2 is the same as defined above; and "c" is an integer ranging from 1 to 3) (component is used in an amount of 0.005 to 10 parts by mass per 100 parts by mass of component). 100 parts by mass of an organopolysiloxane having a viscosity of at least 500 mPa.s at 25°C; 400 to 3,500 parts by mass of a thermally conductive filler; 0.1 to 10 parts by mass of a fine hydrophobized silica powder; an organopolysiloxane represented by the general formula given below and having a viscosity of less than 500 mPa-s at 25°C: R 1 3 SiO (R 1 2 SiO) m, (R 1 R 3 SiO) n R 1 2 Si-X-SiR 1 (3.a) (OR 2) a {wherein X represents an oxygen atom or a bivalent hydrocarbon group having 2 to 10 carbon atoms; R 1 represents identical or different monovalent hydrocarbon groups which are free of unsaturated aliphatic bonds; R 2 represents groups selected from alkyl groups, alkoxyalkyl groups, alkenyl groups, or acyl groups; R 3 is represented by the following general formula: -X-SiR 1 (3-b) (OR 2) b (wherein X, R 1, and R 2 are the same as defined above; and "b" is an integer ranging from 1 to 3); "a" is an integer ranging from 0 to 3; "m" is an integer equal to or greater than 0; and "n" is an integer equal to or greater than 0; however, when "a" is equal to 0, "n" is an integer equal to or greater than 1} (component is used in an amount of 0.005 to 10 parts by mass per 100 parts by mass of component); and a silane compound of the following general formula: R 4 (4-c) Si(OR 2) c (wherein R 4 is a group selected from a monovalent hydrocarbon group, epoxy- containing organic group, methacryl-containing organic group, or an acryl- containing organic group; R 2 is the same as defined above; and "c" is an integer ranging from 1 to 3) (component is used in an amount of 0.005 to 10 parts by mass per 100 parts by mass of component). {wherein X represents an oxygen atom or a bivalent hydrocarbon group having 2 to 10 carbon atoms; R 1 represents identical or different monovalent hydrocarbon groups which are free of unsaturated aliphatic bonds; R 2 represents groups selected from alkyl groups, alkoxyalkyl groups, alkenyl groups, or acyl groups; R 3 is represented by the following general formula: -X-SiR 1 (3-b) (OR 2) b (wherein X, R 1, and R 2 are the same as defined above; and "b" is an integer ranging from 1 to 3); "a" is an integer ranging from 0 to 3; "m" is an integer equal to or greater than 0; and "n" is an integer equal to or greater than 0; however, when "a" is equal to 0, "n" is an integer equal to or greater than 1} (component is used in an amount of 0.005 to 10 parts by mass per 100 parts by mass of component); and a silane compound of the following general formula: R 4 (4-c) Si(OR 2) c (wherein R 4 is a group selected from a monovalent hydrocarbon group, epoxy- containing organic group, methacryl-containing organic group, or an acryl- containing organic group; R 2 is the same as defined above; and "c" is an integer ranging from 1 to 3) (component is used in an amount of 0.005 to 10 parts by mass per 100 parts by mass of component).