PROBLEM TO BE SOLVED: To provide a method for preserving a distillation residual liquid over a long period of time without decaying. SOLUTION: When an ethanol is manufactured by saccharifying a substrate that consists of a biomass with a saccharifying enzyme, fermenting the obtained saccharification solution to obtain a fermented solution, and then distilling the fermented solution, the distillation residual liquid left after the distillation of the fermented solution is recovered, and a calcium cyanamide is added to the distillation residual liquid so that the nitrogen concentration of the calcium cyanamide origin is within a range of 0.08-0.8 mass%. COPYRIGHT: (C)2012,JPO&INPIT
