To provide a evaporative cooling device capable of uniformly and efficiently evaporatively cooling a whole of an article to be cooled.

A cooling fluid conduit 6 is provided in a jacket part 2 of a reaction pot 1. A plurality of cooling fluid spraying ports not shown are provided on the cooling fluid conduit 6 and one end of a cooling fluid feeding pipe 5 is connected to it. The other end of the cooling fluid feeding pipe 5 is connected to a part of a circulation passage 15 of a combined vacuum pump 4. When the reaction pot 1 is cooled, the cooling fluid is fed to the whole of the reaction pot 1 by spraying the cooling fluid from the cooling fluid feeding pipe 5 and the cooling fluid conduit 6 into the jacket part 2. Thereby, the reaction pot 1 can be evaporatively cooled without unevenness.