Provided is a substrate processing apparatus including a chamber including a processing space; a support table provided within the processing space of the chamber and configured to support a substrate; a dielectric plate covering an opening in an upper wall of the chamber; a transparent electrode provided on the dielectric plate; a laser supply head configured to supply a laser beam toward the substrate supported on the support table via the transparent electrode and the dielectric plate; and a cooling device configured to cool the transparent electrode by injecting a cooling gas toward the transparent electrode.