A gas distribution device for a substrate treating apparatus includes a plurality of plasma source electrodes having a first side surface; a plurality of plasma ground electrodes having a second side surface facing the first side surface, the plurality of plasma ground electrodes being alternately arranged with the plurality of plasma source electrodes; and a first gas providing part disposed at each plasma source electrode and including a first space, a plurality of first through-holes in communication with the first space for providing a first process gas between one of the plurality of plasma source electrodes and a corresponding ones of the plurality of plasma ground electrodes, and a first discharging portion at the first side surface.