A head lamp device includes a structure in which a discharge lamp has a discharge bulb and a reflector of a substantially hemispheric shape arranged in an upper part of a housing. A filament including a filament bulb and a reflector of a substantially hemispheric shape is arranged in a lower part of the housing. The front opening of the lamp housing is covered by a front lens. The discharge bulb can generate two to three times as much luminous flux as a conventional filament bulb. As a result, it is possible to reduce the size of the discharge bulb as compared to the filament bulb. This makes it possible to reduce the overall size of the head lamp device.