To use the whole units as a single unit by installing a necessary number of spiral heat transferring part main bodies inside an outward packaged tank.

The air to be condensed, that is introduced from steam introducing hole 5 to an external facing tank 2, flows into each direct and cross path from the upper surfaces of the spiral state opening part of the spiral heat transferring part main bodies 1. The air to be condensed contacts the low temperature spiral heat transferring wall surface, is condensed and the condensed liquid flows downward as drips. The condensed liquid is taken out from the condensed liquid outlet 6 that is arranged at the bottom part of the external facing tank 2 and the uncondensed gas is taken out from the uncondensed gas outlet 7 at the upper part on the side surface. The cooling water supplied to each of the spiral heat transferring part main bodies 1 comes from the cooling water introducing hole 12, goes through the lower part ring shaped connecting pipes 10 and flows into the spiral paths that are closed at the upper and lower ends from the cooling water inlet hole 8. It cools the heat transferring wall surfaces flowing along the paths, reaches each central part, is collected to the upper connecting pipes 11 from a cooling water outlet 9 and flows out from a cooling water outlet hole 13.