57 A hollow-cathode type metal ion laser (100) for producing white light includes a gas-filled tubular envelope (1) and a hollow-cathode (3) located within the tubular envelope (1). The hollow cathode (3) has holes (4) formed in a side wall portion thereof and a bore therein (3a). The hollow-cathode type metal ion laser preferably includes a plurality of metal-containing reservoirs (7) for diffusing vapour of the metal into the bore (3a) through the holes (4). Each of the metal-containing reservoirs (7) forms a portion of the tubular envelope (1) and is preferably disposed next to one of the holes (4). Further, each of the metal-containing reservoirs (7) preferably extends downwardly. Main anodes (5), one near each of the holes, are preferably disposed one within each of the metal-containing reservoirs (7). The tubular envelope (1) preferably includes sub-anodes (6) disposed one within each end portion (1b, 1c) of the tubular envelope (1) to confine the metal vapour within the bore (3a).