An object of the present invention is to provide a lighting method and the like that can prevent a lamp temperature of each individual high-pressure mercury lamp from being beyond a proper temperature range of a halogen cycle. The lighting method maintains a discharge of the high-pressure mercury lamp that has a function of the halogen cycle. The control is performed as follows. From when the high-pressure mercury lamp is lighted up to when a lamp voltage Vla reaches a first voltage value V1, a constant current control is performed. When the lamp voltage Vla reaches the first voltage value V1, the constant current control is switched to a constant power control which is performed at a first power value W1. While the discharge of the lamp is maintained, when the lamp voltage Vla reaches a voltage value (second voltage value V2) at which a state of the halogen cycle deviates from a proper state, the constant power control is performed by reducing the first power value W1 to a second power value W2.