A heat conversion device according to an embodiment of the present invention comprises: a frame comprising multiple unit modules arranged in a first direction and in a second direction intersecting with the first direction, respectively, and a first cooling water inflow tube and a first cooling water discharge tube formed along the first direction so as to support the multiple unit modules; multiple second cooling water inflow tubes connected to the first cooling water inflow tube and arranged on one side of the multiple unit modules along the second direction; and multiple second cooling water discharge tubes connected to the first cooling water discharge tube and arranged on the other side of the multiple unit modules along the second direction. Each unit module comprises a cooling water passage chamber, a first thermoelectric module arranged on a first surface of the cooling water passage chamber, and a second thermoelectric module arranged on a second surface of the cooling water passage chamber. A cooling water inflow port is formed on a third surface between the first and second surfaces of the cooling water passage chamber. A cooling water discharge port is formed on a fourth surface between the first and second surface of the cooling water passage chamber. The cooling water inflow port is connected to the second cooling water inflow tubes, and the cooling water discharge port is connected to the second cooling water discharge tubes.