To enable effectively applying liquids for washing the hair such as shampoo and rinse over a wig part in the case of washing the hair with the wig on a head.

This device is a cap 10 which is attached to the outlet part 2 of a liquid container 1 for washing the hair. A great number of pillar-shaped bodies 13a and 13b with through holes 15a and 15b as holes for the passages of liquids for washing the hair are formed on the cap 10 in the shape of the teeth of a comb. As the pillar-shaped protruding parts 13a and 13b can smoothly reach the net-shaped base part of a wig, injecting liquids for washing the hair to the surface and inside of the net-shaped base part of the wig is reliably performed.