To provide a new thermoelectric semiconductor material which is excellent in thermoelectric properties and restrained from deteriorating in thermoelectric properties like a usual semiconductor material such as PbTe or PbSnTe even if it is enhanced in strength by sintering.

This thermoelectric semiconductor material is represented by a chemical formula, AB2X4 [(where A is a simple substance or a mixture of Pb, Sn, and Ge (IV element), B is a simple substance or a mixture of Bi and Sb (V element), and X is a simple substance or a mixture of Te and Se (VI element)]. In this case, a pulse current is applied to the powdered material 14 by the use of a discharged plasma sintering device 10 to enable electric discharge to take place between particles, and compound AB2X4 of uniform structure is synthesized.