To provide a hair styling method for applying most suitable hair treatment by grasping damage conditions or a degree of health conditions of the hair based on a damage diagnosis from appearance of the hair such as a permanent wave, hair dye, straightening, frequency of shampooing, conditions of care at home, products applied to the hair, or the like.

The damage degree of hair is grasped beforehand from the conditions of a customer's hair. Corresponding to the damage degree, appropriate pretreatment, required softening time, chemical agents acting time of the chemical agents, an ironing temperature and the like are decided. Then, coloring or permanent treatment is applied.