There is disclosed a high-pressure metal-vapor discharge lamp lighting apparatus comprising control circuit constituted to supply a lamp power larger than a rated lamp power from lighting circuit and light a high-pressure metal-vapor discharge lamp and to subsequently control the lighting circuit in such a manner that the lamp power is successively reduced in accordance with predetermined reduction ratio characteristics to settle at the rated lamp power and to be capable of varying the reduction ratio characteristics in accordance with fluctuations of rising characteristics of a quantity of light in the high-pressure metal-vapor discharge lamp.