According to an embodiment, disclosed is a thermoelectric device comprising: a thermoelectric element comprising a first substrate, a plurality of first electrodes disposed on the first substrate, a plurality of P-type thermoelectric legs and a plurality of N-type thermoelectric legs disposed on the plurality of first electrodes, a plurality of second electrodes disposed on the plurality of P-type thermoelectric legs and the plurality of N-type thermoelectric legs, and a second substrate disposed on the plurality of second electrodes; and a heat sink comprising a plurality of fins disposed to be spaced apart on the second substrate, wherein the second substrate comprises a first region overlapping the second electrodes in a vertical direction and a second region not overlapping the second electrodes in the vertical direction, and wherein separation distances between adjacent fins of the plurality of fins are different from each other in the first region and the second region.