To provide a vacuum concentration device in a feed production using a waste liquid produced by the distillation of a B-class Japanese spirit, by performing the vacuum concentration of the waste liquid produced by the distillation of a potato spirit without scorching and not reducing the value as a feed to produce the feed having a high value as the feed by using a vacuum dryer having a same scale to that used for producing a cereal spirit.

This vacuum concentration device in a feed production using a waste liquid produced by the distillation of a B-class Japanese spirit, consists of a jacket (9) having tubular passages in a major tank installed for increasing the amount of a heat transfer Q (kcal/hr) to elevate a vacuum concentration efficiency, a low temperature steam generating device (19) for concentrating the waste liquid which contains gluten, has a high viscosity, and is produced by the distillation of a B-class Japanese spirit without scorching, also an ejector (24) capable of performing ≤10Torr vacuum concentration, a two-staged water sealing-type vacuum pump, etc.