Provided is a short-arc discharge lamp, comprising a housing which has an anode and a cathode arranged facing each other inside a light-emitting tube, the cathode comprising tungsten; and an emitter section which is joined to the leading end of the housing, wherein the short-arc discharge lamp has a construction such that there is little change in the position of the cathode spot and decline in the lamp illuminance can be suppressed, this being achieved by a reduction in the amount of contraction of the cathode main body that accompanies the elapse of ignition time. A short-arc discharge lamp characterized in that the porosity of the cathode main body is less than that of the emitter section.