A thermoelectric module (1) utilizing the Peltier effect, exhibiting an element-occupied area ratio of 40% or below, the element-occupied area ratio defined as the ratio of the sum of cross-sectional areas, perpendicular to the direction of electric current passage, of thermoelectric elements (5a,5b) to the area of insulating substrate (2a) being in contact with an object to be cooled via a metalized layer (4a), wherein metalized layers (4a,4b) are provided with slits. In this construction, there can be prevented breakage of thermoelectric device by thermal stress occurring at assembly, or thermal stress occurring at pre-tinning conducted in advance for attaching an object to be cooled or at attaching package, etc.