A thermoelectric generator has a plurality of hot-side heat source portions, a plurality of cold-side heat source portions, a thermoelectric element, a hot-side communicator and a cold-side communicator. Hot fluid flows in the plurality of hot-side heat source portions, and cold fluid colder than the hot fluid flows in the plurality of cold-side heat source portions. The heat source portions are alternately stacked in such a manner of interposing the thermoelectric element between the hot-side heat source portion and the cold-side heat source portion. The hot-side communicator communicates the hot-side heat source portions, and the cold-side communicator communicates the plurality of cold-side heat source portions. Each of the hot-side communicator and the cold-side communicator has a distance adjuster for adjusting distances between the hot-side heat source portions and the cold-side heat source portions so as to bring them in contact with the thermoelectric elements in the stacking direction thereof.