To provide a bulb fixing structure capable of securing waterproof performance equivalent to or greater than that of the conventional one and attaining space saving in a radial direction.

The bulb fixing structure includes a bulb and a means for fixing a reflector and a housing while the reflector having a through-hole formed for inserting the bulb and a housing through-hole are approximately coincided with each other. The reflector includes a portion engaged with an engagement section of the bulb, and the bulb is fixed with the reflector since the engagement section of the bulb is engaged with the portion of the reflector. A flange section includes a ring-shaped surface opposite to a ring-shaped surface around the housing through-hole. A ring-shaped packing is arranged between the ring-shaped surface around the housing through-hole and that of the flange section, and includes one ring-shaped surface stuck to the ring-shaped surface around the housing through-hole, and the other ring-shaped surface as at the opposite side stuck to that of the flange section.