Method for treating hair

A method for treating hair, comprising:

• treating hair such that the hair is divided into A layer and B layer with a boundary at a depth X %of 5% or more and 80% or less from the surface of the hair toward the center of a cross-section of the hair along the long diameter axis extending through the center of the cross-section of the hair, and that at least one value of color difference ΔE* , hue difference Δh and chroma difference ΔC* between a color of the A layer and a color of the B layer is adjusted to 3 or more to provide visual changes in the hue and the color tone of hair appearance depending on viewing angle of the hair,
• wherein
• the A layer is a portion having a continuous color from the surface of the hair to the depth X % of the hair,
• the B layer is a portion including the center of the hair and having a continuous color different from the color of the A layer, a depth of the B layer from the surface of the hair exceeding X %,
• the color of the A layer is a color dyed by using a dye comprising at least one dye (A) selected from the group consisting of the following (A-1) to (A-8):
• and
• the color of the B layer is a color dyed by using a bleach or an oxidation dye intermediate.