Graphitized carbon powder are produced by carbonizing and expanding a pitch by heating to form carbonaceous foam and by graphitizing before pulverizing or graphitizing after pulverizing the carbonaceous foam. The resultant graphitized carbon powders have an interplanar spacing (d002) of graphite planes of less than 0.3370 nm. The powders preferably have an average particle size of from 2 to 200 &mgr;m. A thermally conductive composition includes the graphitized carbon powders in a matrix. The content of the powders is preferably 1 to 800 parts by weight relative to 100 parts by weight of the matrix. Thus, the graphitized carbon powders that have excellent thermal conductivity and a thermally conductive composition including such powders are provided.