Mounting structure for automotive room lamp

1. A mounting structure for an automotive room lamp, the mounting structure comprising sequentially in the following order from bottom:

an outer housing having a first locking portion;

a ceiling including a lamp opening portion in a central portion thereof;

an inner housing including:

a first locking facing portion which is locked in the first locking portion of the outer housing; and

a second locking portion on and directly attached to the inner housing; and

a reinforcement having a second locking facing portion which is locked on the second locking portion of the inner housing,

wherein the ceiling is fixed between the outer housing and the inner housing by locking the first locking facing portion of the inner housing in the first locking portion of the outer housing via the lamp opening portion in the ceiling, and

wherein a bracket portion shaped so as to follow a shape of an upper side of the ceiling is provided along an outer circumference of the inner housing.

2. The mounting structure for the automotive room lamp as set forth in claim 1 , wherein the ceiling further includes a bottom surface portion which connects to the lamp opening portion in the central portion so as to extend outwards therefrom;

a wall surface portion erected along an outer circumference of the bottom surface portion; and

a flange portion which extends outwards horizontally from the wall surface portion.

3. The mounting structure for the automotive room lamp as set forth in claim 1 , wherein a lock protection member having a height higher than the first locking portion of the outer housing is erected in proximity to the first locking portion.

4. The mounting structure for the automotive room lamp as set forth in claim 3 , wherein the lock protection member has a thickness which is thicker than the first locking portion.

5. The mounting structure for the automotive room lamp as set forth in claim 3 , wherein the lock protection member includes a reinforcement rib.