PURPOSE: To enhance thermoelectric conversion material in mechanical strength without deteriorating it in thermoelectric properties by a method wherein additive through which material is controlled in conductivity type and metal silicide specified in thermal expansion coefficient are added to FeSi2.

CONSTITUTION: Thermoelectric conversion material of Fe(1-x-y)M'xMySi2 is used. M' denotes additive which determines the conductivity type of FeSi2, and M is metal which is contained in material as MSi2 of thermal expansion coefficient 7×10-6 to 11×10-6°C is 0.01 to 0.06, and Y is 0.01 to 0.1. In this thermoelectric conversion material, MSi2 is present at interfaces or in grains. Therefore, when generated cracks hit MSi2, they are changed in propagation directions. That is, this thermoelectric conversion material is increased in mechanical strength. Therefore, this thermoelectric conversion material is excellent in both mechanical and thermal shock, so that it is widened in a field of application.