<p>An illumination device includes a light emitting module (20) and a mounting housing (10) for receiving the light emitting module therein. The light emitting module includes a light guide plate (21) and a light source (23) optically coupled to the light guide plate. The mounting housing includes a top plate (12), a mounting plate (14) and a side plate (16) interconnected between the top plate and the mounting plate. A receiving space (15) is cooperatively formed by the top plate, the mounting plate and the side plate of the mounting housing for receiving the light guide plate therein. A gap (120) is defined in the top plate above the light emitting module. An opening (160) is defined in one end of the side plate for allowing the light emitting module to insert into the receiving space.</p>
