In this study, we investigated the appropriate conditions to extract acidic polysaccharide and to prepare red ginseng extract being rich in acidic polysaccharide from red tail ginseng marc produced after manufacturing alcoholic extract from red tail ginseng. Amount of acidic polysaccharide in red tail ginseng marc was about 11%. The best condition for the extraction of acidic polysaccharide from the marc was using of 3~5 mg of $alpha$-amylase/g residue/15 ml of distilled water, and the amount of acidic polysaccharide in water extract of the residue treated with $alpha$-amylase was about 27%. So, it is possible to manufacture red ginseng extract being rich in acidic polysaccharide using water extract of red tail ginseng alcoholic residue as extraction solvent. From the above results, we suggest that red tail ginseng residue produced by manufacturing alcoholic extract of red tail ginseng has high potencies in the utilization of waste material.