A thermoelectric element is provided as follows. First and second semiconductor fin structures are disposed on a semiconductor substrate. Each semiconductor fin structure extends in a first direction, protruding from the semiconductor substrate. First and second semiconductor nanowires are disposed on the first and second semiconductor fin structures, respectively. The first semiconductor nanowires include first impurities. The second semiconductor nanowires include second impurities different from the first impurities. A first electrode is connected to first ends of the first and second semiconductor nanowires. A second electrode is connected to second ends of the first semiconductor nanowires. A third electrode is connected to second ends of the second semiconductor nanowires.