To treat the hair using water which abundantly exists in the neighborhood, is safe, and costs nearly nothing, and an ion exchange resin film, while conventionally the treating agent and treating method of the hair are to improve fixing of a colorant to the hair, improve the damage to the hair or the hand, or improve unpleasant odor.

The method for treating the hair is to use clean water obtained by filtering water by an activated carbon, a first liquid of pH 10 obtained by using the clean water and an ion exchange resin, a second liquid of pH 4 and a third liquid of pure water. The method includes the step to wind the hair after the shampoo step by a rod while applying the first liquid to the hair, the step to apply a first permanent wave liquid by the mixture of the first permanent wave liquid and the first liquid by 1:1 ratio to the hair after the step to wind the hair by the rod, or a step to apply a colorant by the mixture of a first colorant, a second colorant and the first liquid at 5:4:1 ratio to the hair after the step to apply the first liquid.