A headrest apparatus for vehicle seats. The headrest apparatus includes coupling holders, a support, a headrest, and an actuating unit. The headrest apparatus further includes a connector body mounted outside any one of the coupling holders, and configured to have guide rails that extend from the connector body in the ascending and descending direction of the support; a slider coupled to the connector body so as to be moved along the guide rails; and connectors configured to be respectively mounted to a lower end of the support and the slider, to be coupled to or separated from each other according to the ascent and descent of the support, and to be respectively connected with the power line, which is connected to the actuating unit of the headrest, and the power line, which is connected to the power supply unit of the vehicle via the seat main body.