Abstract: The present invention provides a grease showing low thermal resistance, which is not significantly deteriorated by a heat cycle, particularly, a grease suitable as a thermally conductive material for heat-generating electronic components. A grease containing one type or at least two types of thermally conductive material powder selected from the group consisting of a thermally conductive material (A), a thermally conductive material (B) and a thermally conductive material (C), wherein the particle size distribution of the thermally conductive material powder measured by a laser diffraction type particle size distribution method, has population peaks in the ranges of from 2.0 to 10 ?m, from 1.0 to 1.9 ?m and from 0.1 to 0.9 ?m, respectively, and the grease contains a base oil having a surface tension of from 25 to 40 dyn/cm at 25° C.