A lamp device adapted to be mounted on a vehicle , comprising: a plurality of light sources ; a first sensor configured to sense external information of the vehicle; a lamp housing that houses the light sources; a first sensor housing that houses the first sensor; and a first supporting member that supports the lamp housing and the first sensor housing, wherein the lamp housing and the first sensor housing are arranged in a direction corresponding to a left-right direction of the vehicle when viewed from a direction corresponding to a front-rear direction of the vehicle; and wherein a maximum dimension (UD1, UD5, UD8) of the lamp housing in a direction corresponding to an up-down direction of the vehicle is smaller than a maximum dimension (UD2, UD6, UD9) of the first sensor housing in the same direction, wherein the lamp device further comprises: a second sensor configured to sense external information of the vehicle in a manner that is different from the first sensor ; and a second sensor housing that houses the second sensor, wherein the lamp housing is located between the first sensor housing and the second sensor housing; wherein an upper end of the lamp housing is located below an upper end of the first sensor housing and an upper end of the second sensor housing; and wherein a lower end of the lamp housing is located above a lower end of the first sensor housing and a lower end of the second sensor housing. a plurality of light sources ; a first sensor configured to sense external information of the vehicle; a lamp housing that houses the light sources; a first sensor housing that houses the first sensor; and a first supporting member that supports the lamp housing and the first sensor housing, wherein the lamp housing and the first sensor housing are arranged in a direction corresponding to a left-right direction of the vehicle when viewed from a direction corresponding to a front-rear direction of the vehicle; and wherein a maximum dimension (UD1, UD5, UD8) of the lamp housing in a direction corresponding to an up-down direction of the vehicle is smaller than a maximum dimension (UD2, UD6, UD9) of the first sensor housing in the same direction, wherein the lamp device further comprises: a second sensor configured to sense external information of the vehicle in a manner that is different from the first sensor ; and a second sensor housing that houses the second sensor, wherein the lamp housing is located between the first sensor housing and the second sensor housing; wherein an upper end of the lamp housing is located below an upper end of the first sensor housing and an upper end of the second sensor housing; and wherein a lower end of the lamp housing is located above a lower end of the first sensor housing and a lower end of the second sensor housing. a second sensor configured to sense external information of the vehicle in a manner that is different from the first sensor ; and a second sensor housing that houses the second sensor, wherein the lamp housing is located between the first sensor housing and the second sensor housing; wherein an upper end of the lamp housing is located below an upper end of the first sensor housing and an upper end of the second sensor housing; and wherein a lower end of the lamp housing is located above a lower end of the first sensor housing and a lower end of the second sensor housing. <EOS>