A thermoelectric conversion device includes at least one thermoelectric conversion unit. The thermoelectric conversion unit includes at least one first electrode, at least one second electrode, a P-type thermoelectric material, and an N-type thermoelectric material. The first electrode includes a first fluid channel, such that the first electrode has a first hollow structure. The second electrode includes a second fluid channel, such that the second electrode has a second hollow structure. The P-type thermoelectric material is located between the first electrode and the second electrode, and the second electrode is located between the P-type thermoelectric material and the N-type thermoelectric material.