A thermoelectric conversion material contains a mixed oxide containing Zn, Ga, and In. The thermoelectric conversion material is one in which the mixed oxide further contains Al. The thermoelectric conversion material is one in which the relative density of the mixed oxide is not less than 80%. The thermoelectric conversion material is one in which at least a part of a surface of the mixed oxide is coated with a film. A thermoelectric conversion module is provided with a plurality of n-type thermoelectric conversion materials, a plurality of p-type thermoelectric conversion materials, and a plurality of electrodes electrically serially connecting the p-type thermoelectric conversion materials with the n-type thermoelectric conversion materials in an alternate arrangement, and at least one material of the plurality of n-type thermoelectric conversion materials is the aforementioned thermoelectric conversion material.