A Peltier or Seebeck element has first and second conductive members having different Seebeck coefficients. To decrease the heat conduction from one to the other end of each of the conductive members, the cross-section area at the intermediate part in the length direction is smaller than those at both ends parts. In place of the decrease of the cross-section, the shape of the cross-section of the intermediate part of each of the conductive members may be changed by dividing the intermediate part into pieces, or amorphous silicon or the like having a heat conductivity lower than those of the materials of both end parts may be used for the material of the intermediate part. In such a way, a high-performance Peltier/Seebeck element such that the difference between the temperature of the heated portion of the Peltier/Seebeck element and the opposite portion can be kept to a predetermined temperature difference for a long time and its manufacturing method are provided.