In a cooling device, a condensation unit is constructed by stacking plural unit plates and two outer plates. The plural unit plates are superimposed in a plate-thickness direction between the outer plates, and three sheets of unit plates are also arranged in the planar direction. The radiating fins are provided such that the width of the base is substantially equal to the width of the unit plate, and are arranged in parallel on one of the outer plates in the same manner as the unit plate. According to this structure, the number of the unit plates arranged in parallel with the outer plates and the number of the radiating fins are increased or decreased, so that it is possible to easily change the size of a radiating unit in accordance with a necessary cooling capacity.