Thermally conductive grease composition

A thermally conductive grease composition comprising:

• a matrix resin;
• and
• a thermally conductive filler,
• wherein the matrix resin comprises a liquid dimethylpolysiloxane (A) having a kinematic viscosity in a range from 100 to 10,000 mm2/s at 40° C., and an ethylene-propylene copolymer (B) having a kinematic viscosity in a range from 1 to 10,000 mm2/s at 40° C.,
• the matrix resin comprises the liquid dimethylpolysiloxane (A) in an amount in a range from 50 parts by mass to 97 parts by mass, and the ethylene-propylene copolymer (B) in an amount in a range from 3 parts by mass to 50 parts by mass, where a total amount of the liquid dimethylpolysiloxane (A) and the ethylene-propylene copolymer (B) is 100 parts by mass, and
• the thermally conductive filler is present in an amount in a range from 400 to 2500 parts by mass with respect to 100 parts by mass of the total amount of the liquid dimethylpolysiloxane (A) and the ethylene-propylene copolymer (B).