An in-vehicle light apparatus for monitoring a region in a first direction outside a vehicle, including: a lamp unit including a light source and a reflector; a radar unit including a circuit board disposed such that a board surface extends substantially along the horizontal direction on a lower side or an upper side of the lamp unit and a plurality of antenna elements disposed in the hoard surface of the circuit hoard to transmit an electromagnetic wave in the first direction; and the plurality of the antenna elements are arranged in an array on the first direction side relative to the reflector in plan view, and an array direction of the plurality of antenna elements is a direction intersecting the first direction and non-parallel to an extending direction of an end portion on the side of the first direction of the reflector in plan view.