Abstract: The present invention relates to a polysaccharide composition having the hematopoietic, myeloprotecting, antitumor immune cell generating, and radiosensitizing activities extracted from the roots of Panax ginseng prepared by the steps of: i) obtaining the residue by extracting 1 wt part of ginseng roots with 2˜4 wt part of methanol; ii) extracting and obtaining the water soluble fraction from the residue in step i) using 3˜5 wt part of distilled water; iii) freeze-drying the obtained water soluble fraction in step ii); iv) obtaining the inner fraction using the dialysis membrane after obtaining the insoluble fraction to the 40% of ethanol from freeze-dried fraction in step iii); v) obtaining the 6 fractions by sephacryl S-500 gel chromatography; and vi) purifying the polysaccharide by DEAE-sephadex A-50 chromatography.