A thermoelectric power-generation device includes: a first flow path through which a high-temperature medium flows; a second flow path through which a low-temperature medium that has a temperature difference with respect to the high-temperature medium flows; an insulating isolation plate configured to isolate the first flow path from the second flow path; insulating outer layer isolation plates provided at outermost portions of layered flow paths including the first flow path and the second flow path; a plurality of thermoelectric conversion units configured to generate power using the temperature difference; and electrodes provided at the outer layer isolation plates and configured to connect the thermoelectric conversion units with mutually different semiconductor polarities in series, and the thermoelectric conversion units are disposed so as to straddle the first flow path and the second flow path.