The invention relates to a hair treatment method for treating hair by using a hair treatment tool (1). The hair treatment tool (1) includes: a fiber structure member (5) that retains a hair cosmetic； and a liquid-impermeable sheet (3) to which the fiber structure member (5) is fixed. The fiber structure member (5) retains a hair cosmetic that includes a pigment and a film-forming resin, and is sealed in a packaging (2). The hair treatment method of the invention treats hair by: exposing a surface of the fiber structure member (5) of the hair treatment tool (1)； and bringing the fiber structure member (5) into contact with hair, and in this state, moving the fiber structure member (5) in a direction of orientation of the hair.
