This invention is a composition capable of forming a heat-dissipating member that has high heat resistance and high thermal conductivity. This composition for a heat-dissipating member comprises a thermally conductive first inorganic filler bonded to one end of a first coupling agent, and a thermally conductive second inorganic filler bonded to one end of a second coupling agent, the composition being characterized in that: the other end of the first coupling agent and the other end of the second coupling agent are each bonded to a bifunctional or higher silsesquioxane by a curing treatment, as illustrated in FIG. 2; or at least one of the first coupling agent and the second coupling agent includes, in the structure thereof, a silsesquioxane, and the other end of the first coupling agent and the other end of the second coupling agent are bonded together as illustrated in FIG. 3.