Disclosed is a vehicular headlamp including: a basic lamp unit configured to form a main light distribution pattern that is controlled in light distribution so as to satisfy illuminance requirements at a plurality of predetermined sites in a low beam light distribution pattern which is projected on a vertical virtual screen positioned in front of a vehicle; and a plurality of additional lamp units controlled in light distribution so as to irradiate light to any one of left and right diffusion regions adjacent to the main light distribution pattern. The low beam light distribution pattern is formed on the vertical virtual screen by combining the basic lamp unit and the plurality of additional lamp units.