There is provided a high-intensity discharge lamp lighting apparatus to be loaded with a plurality of types of high-intensity discharge lamps and connected with any one of the lamps to be lighted, and the apparatus comprises a power conversion circuit for converting power supplied from a DC power source to supply the power to a high-intensity discharge lamp and a lighting control circuit for controlling the supply power of the power conversion circuit, wherein the type of the connected high-pressure discharge lamp is determined based upon a change rate of an electric characteristic of the high-intensity discharge lamp during a specific period, and the connected high-intensity discharge lamp is lighted with a desired electric characteristic selected based upon the determination result, thereby enabling discrimination of types of rated power of the plurality of types of lamps by the same detection method and the same control method irrespective of states in starting of the lamps, and by enabling the discrimination before stable lighting of the lamp, it is possible to start the discharge lamp with little stress applied to the discharge lamp.