A metal halide lamp includes a refractory, light-transmitting hermetic vessel, a pair of electrodes sealed in thehermetic vessel, a discharge medium including a halide and a rare gas, and metal storing means storing at least one selected from the group consisting of potassium (K), rubidium (Rb) and cesium (Cs), the metal storing means being heated during lighting and gradually discharging at least one metal in the hermetic vessel.