A headlamp unit is provided to emphasize a shape of an individual lamp while suppressing an increase in the number of parts used, while improving ventilation and preventing fogging in areas near an inner surface of a lens, while maintaining a simple housing structure. The headlamp unit including a high beam lamp and a low beam lamp arranged vertically. The high beam lamp and the low beam lamp are disposed on upper and lower portions, respectively. The headlamp unit including an area between the high beam lamp and the low beam lamp covered with a lamp to lamp transverse portion of a front cowl, and an area near each of lenses including an air vent hole disposed so as to face a space between the two lenses. The headlamp unit may further include a moisture conditioning member disposed on an inside of the lamp housing.