One formula hair dye constituent of the invention is to contain (A) 5,6- dihydroxy indole and 5, the combination of 6- dihydroxy indole -2- carboxylic acid; (B) any in (b1) ascorbic acid or its salt, (b2) sulfurous acid or its salt; And (C) alkali agent; And pH8 ~ 11. It is selected using the type of ingredient (B), and adjusts the method through contaminating the obtained tone of hair Hou.本發明的一劑式染毛劑組成物,係含有:(A)5,6-二羥基吲哚與5,6-二羥基吲哚-2-羧酸的組合;(B)(b1)抗壞血酸或其鹽、(b2)亞硫酸或其鹽中任一;以及(C)鹼劑;且pH8~11。利用成分(B)的種類選擇,而調整經染毛後所獲得色調的方法。