Polysaccharide mixture xylan and g1ucomannan were prepared from the waste water of the steeping alkali solution of wood pulp in a better yield and in higher purity than by the conventional methods. Concentrated waste water, adjusted to 7.5-10% sodium hydroxide concentration, produced a flocculent precipitate by the addition qf excess methanol. This precipitate had a good filtrability to be recovered on Buchner funnel. Graded hydrolysis of this precipitate with hydrochloric acid in methanol gave ash-free polysaccharide mixture, mainly composed of D-xylose, D-mannose, and D-glucose, and free from L-arabinose. Xylan was recovered from water dispersion of polysaccharide mixture as a precipitate. Glucomannan in the supernatant was recovered by fractional precipitation with methanol.