To obtain a condenser for distillation, whose cooling heat transfer area as well as cooling temperature are changeable and which can be used sufficiently not only for a conventional batch type distillation tower, requiring the distillation of many kinds of products principally, but also a continuous distillation tower.

In a multi-tubular heat exchanger 1, cooling medium is passed through the side of a shell while vapor is introduced into the side of tubes 5 to cool and condense the vapor. In this case, the vapor is cooled in a condenser by the evaporating latent heat of the cooling medium and a condensing means 14, condensing the vapor of evaporated cooling medium, is provided to circulate the cooling medium while a pressure changing means 15, changing a pressure in the space of the side of shell, is provided to vary the amount of cooling medium and a pressure in the space at the side of the shell.