A headlamp (10R,10L) for a vehicle, the headlamp (10R,10L) comprising: a lamp body having an opening portion; a transparent cover attached to the opening portion of the lamp body to form a lamp chamber, an outer side portion of the transparent cover with respect to a width direction of the vehicle extending toward a rear side of the vehicle when the headlamp (10R,10L) is mounted on the vehicle; and a plurality of lamp units (30R,40R,50R:30L,40L,50L) arranged inside the lamp chamber along a width direction of the vehicle when mounted, wherein each of the lamp units (30R,40R,50R:30L,40L,50L) comprises: a light emitting element disposed such that a light emitting surface thereof faces an inner side in the width direction of the vehicle when mounted; and a reflector (34R,44R, 54R:34L,44L,54L) disposed on an inner side of the light emitting element with respect to the width direction of the vehicle (20 when mounted) to forwardly reflect light from the corresponding light emitting element, wherein the plurality of lamp units (30R,40R,50R:30L,40L,50L) comprises a first lamp unit (40R,40L) configured to irradiate light forming a horizontal cut-off of a low-beam light distribution pattern; characterised in that the plurality of lamp units (30R,40R,50R:30L,40L,50L) further comprises: a second lamp unit (30R,30L) configured to irradiate light forming an oblique cut-off line of the low-beam light distribution pattern; and a third lamp unit (50R,50L) configured to irradiate light forming a diffused light distribution pattern (Pc,Pf) extending in a horizontal direction below the horizontal cut-off line and the oblique cut-off line. a lamp body having an opening portion; a transparent cover attached to the opening portion of the lamp body to form a lamp chamber, an outer side portion of the transparent cover with respect to a width direction of the vehicle extending toward a rear side of the vehicle when the headlamp (10R,10L) is mounted on the vehicle; and a plurality of lamp units (30R,40R,50R:30L,40L,50L) arranged inside the lamp chamber along a width direction of the vehicle when mounted, wherein each of the lamp units (30R,40R,50R:30L,40L,50L) comprises: a light emitting element disposed such that a light emitting surface thereof faces an inner side in the width direction of the vehicle when mounted; and a reflector (34R,44R, 54R:34L,44L,54L) disposed on an inner side of the light emitting element with respect to the width direction of the vehicle (20 when mounted) to forwardly reflect light from the corresponding light emitting element, a light emitting element disposed such that a light emitting surface thereof faces an inner side in the width direction of the vehicle when mounted; and a reflector (34R,44R, 54R:34L,44L,54L) disposed on an inner side of the light emitting element with respect to the width direction of the vehicle (20 when mounted) to forwardly reflect light from the corresponding light emitting element, wherein the plurality of lamp units (30R,40R,50R:30L,40L,50L) comprises a first lamp unit (40R,40L) configured to irradiate light forming a horizontal cut-off of a low-beam light distribution pattern; characterised in that the plurality of lamp units (30R,40R,50R:30L,40L,50L) further comprises: a second lamp unit (30R,30L) configured to irradiate light forming an oblique cut-off line of the low-beam light distribution pattern; and a third lamp unit (50R,50L) configured to irradiate light forming a diffused light distribution pattern (Pc,Pf) extending in a horizontal direction below the horizontal cut-off line and the oblique cut-off line. a second lamp unit (30R,30L) configured to irradiate light forming an oblique cut-off line of the low-beam light distribution pattern; and a third lamp unit (50R,50L) configured to irradiate light forming a diffused light distribution pattern (Pc,Pf) extending in a horizontal direction below the horizontal cut-off line and the oblique cut-off line.