A device for treating human keratinous materials includes an electrical appliance comprising a handpiece and a reader, and an applicator suitable for being removably fastened on the handpiece. The applicator includes a solid cosmetic or dermatological composition for applying to the keratinous materials, and/or an applicator element including fibers and/or cells suitable for enabling a cosmetic or dermatological composition to be applied on keratinous materials. The applicator also includes an encoder for encoding information arranged to be read by the reader. The operation of the handpiece depends on the information read.