When a pitch composition prepared by mixing 100 parts by weight of mesophase pitch with 10 to 1,000 parts by weight of coal tar pitch, is heat-treated at a temperature of 500 C. or higher, it is possible to produce a high-density coke at a high yield while avoiding the foaming of the mesophase pitch. In addition, when the coke is graphitized at a temperature of 2,000 C. or higher, it is possible to obtain an artificial graphite having a high graphitization degree. Further, when the coke is first pulverized and then graphitized at a temperature of 2,000 C. or higher, it is possible to obtain a high-crystallinity graphite powder which can be suitably used as a carbon material for a negative electrode of non-aqueous solvent type secondary battery having a high discharge capacity and a high charge-discharge efficiency.