A headlight, comprising: an LED device including at least one LED chip (37~40) and at least one LED board (35, 36) electrically connected to the at least one LED chip; a housing including an opening opened forward, the housing accommodating the LED device; a reflector member accommodated in the housing, the reflector member reflecting a light irradiated from the at least one LED chip; and a clear cover covering the opening of the housing, the clear cover permitting the light irradiated from the at least one LED chip (37~40) to forwardly pass therethrough, wherein the reflector member includes a rear wall portion (43, 44) at least partially disposed rearward of the at least one LED chip, a circumferential wall portion forwardly extending from the rear wall portion (43, 44), the circumferential wall portion extending circumferentially about an axis extending in a back-and-forth direction, a protruding portion forwardly protruding from the rear wall portion (43, 44) while being disposed radially inward of the circumferential wall portion, and a rib portion (47, 48) extending in a radial direction of the circumferential wall portion, the rib portion (47, 48) being connected to the protruding portion and the circumferential wall portion, the reflector member includes a board mount space in which the at least one LED board (35, 36) is disposed, the board mount space includes a first space produced inside the protruding portion, and a second space (S5, S6) produced inside the rib portion (47, 48), the second space (S5, S6) communicating with the first space, the rib portion (47, 48) includes a left rib portion extending leftward from the protruding portion in a front view, and a right rib portion extending rightward from the protruding portion in the front view, and the rib portion (47, 48) and the protruding portion divide a space enclosed by the circumferential wall portion into an upper space and a lower space in the front view, characterized in that in a thickness direction of the rib portion (47, 48), the rib portion (47, 48) has a dimension smaller than a dimension of the protruding portion. an LED device including at least one LED chip (37~40) and at least one LED board (35, 36) electrically connected to the at least one LED chip; a housing including an opening opened forward, the housing accommodating the LED device; a reflector member accommodated in the housing, the reflector member reflecting a light irradiated from the at least one LED chip; and a clear cover covering the opening of the housing, the clear cover permitting the light irradiated from the at least one LED chip (37~40) to forwardly pass therethrough, wherein the reflector member includes a rear wall portion (43, 44) at least partially disposed rearward of the at least one LED chip, a circumferential wall portion forwardly extending from the rear wall portion (43, 44), the circumferential wall portion extending circumferentially about an axis extending in a back-and-forth direction, a protruding portion forwardly protruding from the rear wall portion (43, 44) while being disposed radially inward of the circumferential wall portion, and a rib portion (47, 48) extending in a radial direction of the circumferential wall portion, the rib portion (47, 48) being connected to the protruding portion and the circumferential wall portion, a rear wall portion (43, 44) at least partially disposed rearward of the at least one LED chip, a circumferential wall portion forwardly extending from the rear wall portion (43, 44), the circumferential wall portion extending circumferentially about an axis extending in a back-and-forth direction, a protruding portion forwardly protruding from the rear wall portion (43, 44) while being disposed radially inward of the circumferential wall portion, and a rib portion (47, 48) extending in a radial direction of the circumferential wall portion, the rib portion (47, 48) being connected to the protruding portion and the circumferential wall portion, the reflector member includes a board mount space in which the at least one LED board (35, 36) is disposed, the board mount space includes a first space produced inside the protruding portion, and a second space (S5, S6) produced inside the rib portion (47, 48), the second space (S5, S6) communicating with the first space, a first space produced inside the protruding portion, and a second space (S5, S6) produced inside the rib portion (47, 48), the second space (S5, S6) communicating with the first space, the rib portion (47, 48) includes a left rib portion extending leftward from the protruding portion in a front view, and a right rib portion extending rightward from the protruding portion in the front view, and a left rib portion extending leftward from the protruding portion in a front view, and a right rib portion extending rightward from the protruding portion in the front view, and the rib portion (47, 48) and the protruding portion divide a space enclosed by the circumferential wall portion into an upper space and a lower space in the front view, characterized in that in a thickness direction of the rib portion (47, 48), the rib portion (47, 48) has a dimension smaller than a dimension of the protruding portion.