The method for colorimetric determination of acidic polysaccharide from Panax ginseng was investigated. It is possible to apply the method of carbazole-sulfuric acid to determination of pectin, and also to measure the amount of pectin in the mixture of various high molemlu compounds such as starch. cellulose and gum, etc. When the method of carbazole-sulfuric acid was applied to determine the amount of acidic polysaccharide, optical density at 525 nm increased linearly with an increase in the concentration of pure acidic polysaccharide. Effective extraction temperature with water for the determination of the amount of ginseng acidic polysaccharide (GAP) was $80{circ}C$. In order to separate or concentrate GAP it was appropriate to precipitate the extract only once with 80% ethyl alcohol. GAP was very stable at $100{circ}C$ for 4 hrs in aqueous solution and between pH values of 5.0~ 12.0.