PURPOSE: To prevent the damage of the hair and to sustain a permanent treatment over a long period by putting a treatment agent into which protein to prevent runoff into the hair cortex is incorporated into a dissolved state and penetrating the agent into the hair, then applying the treatment agent for protection on the surface of the hair and making operation by using a hair iron.

CONSTITUTION: The hair is subjected to the conventional operation method and is simultaneously heated by a steamer. The set temp. of the steamer is about 50°C and the heating time is set at about 15 to 20 minutes. The treatment agent contg. the protein to prevent the runoff is applied on the surface of the hair, by which the protein to prevent the runoff is dissolved and penetrated in place of the mesenchymal material. The treatment agent for protecting the hair iron is then applied on the surface of the hair and the hair is permed by the heat of the hair iron. The chemical change by the high heat of the hair iron is applied to the protein penetrated into the hair cortex in such a manner, by which the protein is thermally solidified and the elution thereof is prevented.