PURPOSE: To dispense with a level fitting space above a headlamp by fitting a level measuring the inclination of the vertical illumination angle of the headlamp to the horizontal extension section of a socket fixture fitted into a bulb insertion hole, and extending it behind the lamp.
CONSTITUTION: A bubble tube 90 suspended and supported by a cover body 84 made of elastic synthetic resin such as U-polymer and polyacetal in a rectangular container-shaped casing made of synthetic resin and opened upward of a level 80, which is elastically assembled to the horizontal extension section 56 of a socket fixture 50 by a plate spring 96. The cover body 84 is fitted and fixed to the casing 81 by irregular lance coupling and an adjusting screw. A rectangular opening section 82 is formed on a side wall 81a at the rear end of the casing 81, and a hook 83a protruded vertically downward and coupled with the opening section 82 on the casing 81 side is formed at the rear end section of the cover body 84. No level fitting space is required above a headlamp.