A thermoelectric conversion device including an n-type thermoelectric converter, a p-type thermoelectric converter, a high temperature-side electrode with which one end of the n-type thermoelectric converter and one end of the p-type thermoelectric converter are put into contact, a first low temperature-side electrode in contact with another end of the n-type thermoelectric converter, and a second low temperature-side electrode in contact with another end of the p-type thermoelectric converter, wherein in the n-type thermoelectric converter, the side in contact with the high temperature-side electrode is composed of a carrier generation semiconductor containing Mg2Sn, and in the n-type thermoelectric converter, the side in contact with the first low temperature-side electrode is composed of a carrier transfer semiconductor containing Mg2Si1-xSnx, wherein 0.6≤x≤0.7, and a first n-type dopant.