The effect of gamma-pre-irradiation of cellulose in cellulose-containing waste plants was investigated through enzymatic and acidic hydrolysis reaction. Pre-irradiation of waste rice straw, chaff and saw dust accelerated the enzymatic hydrolysis by cellulase. Reducing sugar and glucose yields were higher with an increasing radiation dose in these materials. The required dose for effective acceleration of enzymatic hydrolysis was much reduced by the addition of chlorine during radiation. However, reducing sugar and glucose yields in the subsequent acidic hydrolysis of waste products decreased through pre-irradiation treatment. This was attributed to an acceleration effect of a secondary acidic decomposition of sugar to lower molecular weight-products through pre-irradiation.