A thermoelectric conversion element module (101) includes: a heat receiving part (3) disposed so as to be contactable with a heat source; a thermoelectric conversion element (10) having a first surface (10a) and a second surface (10b), the first surface (10a) being disposed in contact with the heat receiving part (3); and a heat radiating part (5) that is disposed in contact with the second surface (10b) and has an inner space (21).