A headlight unit for a vehicle adapted to lean into turns comprising: a first light source (11L C) adapted to cast light forward in front of the vehicle; and a plurality of second light sources (11L L, 11L R, 13La-Lc, 13Ra-Rc) adapted to cast light forward and outward of the vehicle on one side of the width direction of the vehicle, wherein the plurality of second light sources (11L L, 11L R, 13La-Lc, 13Ra-Rc) has illumination ranges positioned outward of an illumination range of the first light source (11L C) and at different positions relative to the vertical direction of the vehicle in the upright state of the vehicle; a detection unit for detecting a variable according to a lean angle of the vehicle, a control unit for varying the brightnesses of the second light sources (11L L, 11L R, 13La-Lc, 13Ra-Rc) according to the lean angle of the vehicle based on the variable detected by the detection unit, wherein the second light sources (11L L, 11L R, 13La-Lc, 13Ra-Rc) are controlled to achieve predetermined brightnesses when the lean angle of the vehicle is at a reference value individually set for each of the second light sources (11L L, 11L R, 13La-Lc, 13Ra-Rc), characterized in that the illumination ranges of the second light sources (11L L, 11L R, 13La-Lc, 13Ra-Rc) are positioned further upward for the second light sources (11L L, 11L R, 13La-Lc, 13Ra-Rc) having larger reference values in the upright state of the vehicle, and when the lean angle of the vehicle reaches a specific value greater than the reference value set for one of the second light sources (11L L, 11L R, 13La-Lc, 13Ra-Rc), and the first light source (11L C) and an upper second light source having a larger reference value than the one of the second light source are on, the one of the second light sources (11L L, 11L R, 13La-Lc, 13Ra-Rc) is controlled to become darker than the predetermined brightness. a first light source (11L C) adapted to cast light forward in front of the vehicle; and a plurality of second light sources (11L L, 11L R, 13La-Lc, 13Ra-Rc) adapted to cast light forward and outward of the vehicle on one side of the width direction of the vehicle, wherein the plurality of second light sources (11L L, 11L R, 13La-Lc, 13Ra-Rc) has illumination ranges positioned outward of an illumination range of the first light source (11L C) and at different positions relative to the vertical direction of the vehicle in the upright state of the vehicle; a detection unit for detecting a variable according to a lean angle of the vehicle, a control unit for varying the brightnesses of the second light sources (11L L, 11L R, 13La-Lc, 13Ra-Rc) according to the lean angle of the vehicle based on the variable detected by the detection unit, wherein the second light sources (11L L, 11L R, 13La-Lc, 13Ra-Rc) are controlled to achieve predetermined brightnesses when the lean angle of the vehicle is at a reference value individually set for each of the second light sources (11L L, 11L R, 13La-Lc, 13Ra-Rc), characterized in that the illumination ranges of the second light sources (11L L, 11L R, 13La-Lc, 13Ra-Rc) are positioned further upward for the second light sources (11L L, 11L R, 13La-Lc, 13Ra-Rc) having larger reference values in the upright state of the vehicle, and when the lean angle of the vehicle reaches a specific value greater than the reference value set for one of the second light sources (11L L, 11L R, 13La-Lc, 13Ra-Rc), and the first light source (11L C) and an upper second light source having a larger reference value than the one of the second light source are on, the one of the second light sources (11L L, 11L R, 13La-Lc, 13Ra-Rc) is controlled to become darker than the predetermined brightness.