For restoration of historic papers damaged by vermiculation, it is preferable that the quality of paper used for repair resembles that of the original. This study aimed to make good quality paper for repairing historic objects made of paper using gamma irradiation method (*h60*sCo, 49-390 kGy) and thermal accelerated deterioration method (80°C, 60per thousandRH). In addition, treatment by combining both methods was tested to see the effect. Four kinds of washi (Japanese papers), such as kozo (thin and thick), mitsumata and gampi papers, were used in this experiment. Discoloration of the papers after each single treatment was small, while that after gamma irradiation followed by thermal treatment was large. Folding endurance and tensile energy absorption (TEA) were extensively decreased by gamma irradiation. In this case, it was found that these changes in physical property showed the effect of gamma irradiation followed by thermal treatment.