There is provided a lighting device which is to be mounted on a vehicle. The lighting device includes: a housing forming a lamp chamber, the housing including a wall having an opening therethrough; a light source which is disposed in the lamp chamber; a heat sink, wherein the light source is fixed to the heat sink; a fixation portion, wherein the heat sink is fixed to the housing via the fixation portion. A first portion of the heat sink faces an inner surface of the wall. A second portion of the heat sink is exposed to an outside of the wall through the opening. The fixation portion is provided on the outside of the wall to face the opening.