On a top surface of a substrate, a first and a second electrode are formed. A p-type semiconductor film is formed over substantially the entire exposed area on the top surface of the substrate and over the first electrode. An n-type semiconductor film is also formed over substantially the entire surface, but does not cover the first electrode, the p-type semiconductor film and the second electrode. A junction surface between the p-type and n-type semiconductor films extends over substantially the entire substrate, thereby providing a thermoelectric device which can cool or heat a wide surface area. The inclusion of the junction surface between p-type and n-type films, which extends over substantially the entire surface of the substrate, provides a unit whose top surface serves as a heat-absorbing portion and whose bottom surface serves as a heat-releasing portion. Further, by laying a plurality of such units one over the other with insulating material between them, a cascade-type thermoelectric module is obtained.