To obtain water resistance in extruded corn starch, additions of polysaccharides konjac and curdlan were examined. Solubility of extrudates increased as the starch moisture content decreased. Solubility of extruded starch with 3% curdlan added was 38% of that of control. On the other hand, in case of addition of konjac, solubility of extrudates was increased regardless of additive amount. Solubility of extrudates was linearly related to expansion ratio, specific volume, swelling power and shear strength. It was suggested that the structure of extrudates with addition of curdlan were tight and more resistant to absorption of water than the control. Solubility of ground extrudates was linearly related to that of intact extrudates. Extrudates with addition of curdlan exhibited rigid surface and internal structures.