PROBLEM TO BE SOLVED: To provide a polymer material which is not accompanied by the strength deterioration of a material, and excels in durability, and to which water absorptivity, hydrophilicity, adhesion, printability, antistatic property or the like is given to be modified.SOLUTION: The modified polymer material is obtained by a modifying method. The modifying method is characterized by a step (1) of treating a polymer material by a solvent or impregnating treatment, a step (2) of activating the polymer material, a step (3) of treating the polymer material with a polymer solution under the presence of a catalyst or an initiator, a step (4) of carrying out grafting a monomer on the polymer material, and a step (5) of cleaning the grafted polymer material, in the order.
