A lighting device mounted on a vehicular interior part includes a light source having a light exit surface, an elongated light guide member having a light entrance surface opposite the light exit surface of the light source and through which light from the light source enters, and a light exit surface through which the light exits, the elongated light guide member including an elongated core member having an end surface that is the light entrance surface, and a cover member covering an outer peripheral surface of the elongated core member, and the lighting device further includes a positioning member positioning the light entrance surface of the elongated light guide member with respect to the light source, and including a contact portion that is in contact with an outer peripheral edge portion of the end surface of the elongated core member and is not in contact with the cover member.