In an activated gas generation apparatus, metal electrodes are formed on a bottom surface of a dielectric electrode, and are disposed so as to face each other with a central region of the dielectric electrode interposed therebetween in plan view. The metal electrodes face each other along the Y direction. A wedge-shaped stepped part is provided so as to protrude upward in the central region on an upper surface of the dielectric electrode. The wedge-shaped stepped part is formed so as to have a shorter formation width in the Y direction as approaching each of a plurality of gas spray holes in plan view.