To improve the ratio between first and second halides sealed in a mercury-free lamp, thereby providing a
metal halide lamp which has a high luminous efficiency and a low lamp
voltage reduction and emits light of an appropriate color and an automotive
headlamp apparatus incorporating the same. A
metal halide lamp includes a hermetic vessel 1 which is fire resistant and translucent; a pair of electrodes 3, 3 sealed in the hermetic vessel with facing each other at a distant of 5 mm or less; and a
discharge medium substantially containing no mercury, sealed in the hermetic vessel 1, and containing first halides mainly including
scandium halide and
sodium halide, a second halide for mainly providing a lamp
voltage and a
xenon gas at 5 atmospheres or higher at a temperature of 25° C., the amounts of
scandium halide and
sodium halide sealed in the hermetic vessel satisfying the formula of 0.25<a / (a+b)<0.5, where reference character a denotes the
mass of
scandium halide and reference character b denotes the
mass of
sodium halide, in which, in a
stable state, the
metal halide lamp is turned on with a lamp power of 60 W or lower.