According to one embodiment, a thermoelectric conversion device includes a first stacked body comprising a plurality of first semiconductor layers of a first conductivity type, the first semiconductor layers spaced from each other in a first direction, a second stacked body comprising a plurality of second semiconductor layers of a second conductivity type, the second semiconductor layers spaced from each other in the first direction, and a first connection portion electrically connecting the first stacked body to the second stacked body, wherein the first stacked body has a plurality of first openings that extend inwardly of the first stacked body in the first direction, wherein a direction from the first stacked body to the second stacked body intersects the first direction, and wherein the second stacked body has a plurality of second openings extending inwardly of the second stacked body in the first direction.