The Annals of the Joseon Dynasty are the most representative paper heritages made of Hanji, Korean traditional paper, and they have been registered as the Memory of the World by UNESCO. Unfortunately, however, the Annals treated with beeswax have serious damages such as crack and discoloration, although others treated with no beeswax have been keeping those quality during over several hundred years. Therefore, it is necessary to study technical development about dewaxing treatment and strength reinforcement treatment for restoring the Annals of the Joseon Dynasty. In this study, the strength reinforcement by cellulose ether mixed with CMC, MC, EC, cationic starch and chitosan built up the mechanical strength of ageing Hanji, such as folding endurance, tensile strength, and zero-span tensile strength. Also, with the comparison between untreated ageing Hanji and strength reinforced ageing Hanji after ageing treatment, the treatment of strength reinforcement has had safety and stability to the ageing in oxidation index, crystallinity, viscosity, and in mechanical strength properties.