A high dielectric insulating silicone rubber composition comprising: 100 parts by weight of an organopolysiloxane of average compositional formula below that includes at least two silicon-bonded alkenyl groups on the molecule: R 1 n SiO (4-n)/2 wherein each R 1 is the same or different, substituted or unsubstituted monovalent hydrocarbon group, and n is a positive number from 1.95 to 2.04, 60 to 150 parts by weight of thermal black having an average primary particle size of from 150 to 500 nm, being a value measured with a transmission electron microscope, 5 to 100 parts by weight of reinforcing fumed silica having a specific surface area as measured by the BET adsorption method of at least 50 m 2 /g, and 0.1 to 10 parts by weight of a curing agent, being (D-1) an organic peroxide curing agent and/or (D-2) an addition reaction curing agent comprising: an organohydrogenpolysiloxane of average compositional formula below: R 20 p H q SiO (4-p-q)/2, wherein each R 20 is the same or different, substituted or unsubstituted monovalent hydrocarbon group, and p and q are positive numbers which satisfy the conditions 0 < p < 3, 0 < q < 3 and 0 < p+q≤ 3, and a hydrosilylation catalyst; wherein the silicone rubber composition, when cured, has a dielectric constant of 10 or more, a dielectric loss tangent of 0.1 or less, both being measured using an automatic Schering Bridge, a volume resistivity of from 1.0×10 13 to 1.0×10 17 Ω·cm, being measured as disclosed in the description in accordance with JIS K 6249:2003, and a dielectric breakdown strength of 7 kV/mm or more, being measured as disclosed in the description in accordance with JIS K 6249:2003, 100 parts by weight of an organopolysiloxane of average compositional formula below that includes at least two silicon-bonded alkenyl groups on the molecule: R 1 n SiO (4-n)/2 wherein each R 1 is the same or different, substituted or unsubstituted monovalent hydrocarbon group, and n is a positive number from 1.95 to 2.04, 60 to 150 parts by weight of thermal black having an average primary particle size of from 150 to 500 nm, being a value measured with a transmission electron microscope, 5 to 100 parts by weight of reinforcing fumed silica having a specific surface area as measured by the BET adsorption method of at least 50 m 2 /g, and 0.1 to 10 parts by weight of a curing agent, being (D-1) an organic peroxide curing agent and/or (D-2) an addition reaction curing agent comprising: an organohydrogenpolysiloxane of average compositional formula below: R 20 p H q SiO (4-p-q)/2, wherein each R 20 is the same or different, substituted or unsubstituted monovalent hydrocarbon group, and p and q are positive numbers which satisfy the conditions 0 < p < 3, 0 < q < 3 and 0 < p+q≤ 3, and a hydrosilylation catalyst; wherein the silicone rubber composition, when cured, has a dielectric constant of 10 or more, a dielectric loss tangent of 0.1 or less, both being measured using an automatic Schering Bridge, a volume resistivity of from 1.0×10 13 to 1.0×10 17 Ω·cm, being measured as disclosed in the description in accordance with JIS K 6249:2003, and a dielectric breakdown strength of 7 kV/mm or more, being measured as disclosed in the description in accordance with JIS K 6249:2003, an organohydrogenpolysiloxane of average compositional formula below: R 20 p H q SiO (4-p-q)/2, wherein each R 20 is the same or different, substituted or unsubstituted monovalent hydrocarbon group, and p and q are positive numbers which satisfy the conditions 0 < p < 3, 0 < q < 3 and 0 < p+q≤ 3, and a hydrosilylation catalyst;