The present invention relates to a thermoelectric material containing CoSb 3 compound for converting heat to electricity, and provides a p-type thermoelectric material of CoSb 3 having a high power factor by achieving high Seebeck coefficient consistently with high electric conductivity in a material of CoSb 3 system without causing increase in heat conductivity. By sintering Co 0.07 Pt 0.03 Sb 3 alloy powder using the spark plasma sintering technique, the material is densified, while growth of grains is restricted, so that a higher electric conductivity is achieved with a heat conductivity maintained in a low level, and the figure of merit as a heat-transfer material is improved. Also, by providing such heat insulating layer as an oxide intermediately in a grain boundary of a compound of CoSb 3 in a sintered body, the heat conductivity is reduced. Further, the Seebeck coefficient is increased by adding a rare earth metal to the thermoelectric material of CoSb 3 , and allowing it to be precipitated in grain boundaries of the sintered body.