To provide a motor-driven hair comb optimal for a variety of treatments for permeating liquid medicine, such as hair treatment, into the hair.

The motor-driven hair comb 1 includes a comb 2 having a plurality of comb teeth and a grip 4, one end of the comb 2 is fixed to the end of the grip 4, is operation joined to a motor-driven drive mechanism 3 built in the grip 4, and the comb 2 is moved back and forth in an arranged direction of the teeth 21. A prescribed length suited for combing the hair by 1 pitch of the comb teeth 21 of the comb 2 is selected, an amplitude of the movement back and forth of the comb 2 is set to almost one pitch of the comb teeth 21, and the number of movements back and forth is set to a range from 40 to 50 times per second.