VEHICULAR HEADLIGHT

A vehicular headlight (20) includes a first light source unit (41), a second light source unit (61), a temperature sensor (47), and a control unit (110). When the temperature derating is performed on the first light source unit (41) based on the temperature in a state where the light distribution pattern (910) of a low-beam is formed, the control unit (110) controls the power to be supplied to each of a plurality of light-emitting elements (43) so that the light amount of at least a part of the first light with which at least a region (911) of a first light distribution pattern (400) is irradiated decreases as compared with that before the temperature derating.