The present invention provides a thermoelectric conversion material represented by the following chemical formula (I): Ba8+aCu6−bGe40+6   (I) wherein the values of a is not less than 0.1 and not more than 0.47; the values of b is not less than 0 and not more than 0.43; the thermoelectric conversion material has a clathrate crystal structure; and the thermoelectric conversion material is of p-type. The present invention provides a p-type Ba—Cu—Ge clathrate thermoelectric conversion material having high thermoelectric conversion performance index.