The invention provides a method of fabricating a thermoelectric device, whereby a grooved block composed of n-type thermoelectric semiconductor and a grooved block composed of p-type thermoelectric semiconductor, provided with a plurality of grooves formed therein, respectively, at a same pitch and parallel with each other, are formed such that a depthwise portion of respective grooved blocks is left intact, and then, an integrated block is formed by fitting and adhering together the grooved blocks composed of the n-type and p-type thermoelectric semiconductors, respectively, filling up gaps in fitting parts with adhesive insulation members. After removing portions of the integrated block, other than the fitting parts where the n-type and p-type thermoelectric semiconductors are fitted to each other, n-type and p-type thermoelectric semiconductor pieces are exposed, and by forming electrodes for connecting the pieces to each other alternately and in series, the thermoelectric device is completed.