PURPOSE: To allow performing mounting and removal easily only by elastic deformation of the legs 24, 24 of a spring member 22, decrease the number of component parts, and enhance the manufacturability.

CONSTITUTION: A pawl 12 on the second louver plate 4b is threaded through a detention hole 10 provided in the first louver plate 4a and folded so that a louver body 5 is assembled. The central part approximately of the louver body 5 is free from joining of the first and second louver plates 4a, 4b, and a mounting hole 13 is formed dividedly by the side faces of the second louver plate 4b. The louver body 5 is installed on the inside of the outer frame consisting of frame members which are erected into a frame form, and the trunk part 23 of a spring member 22 is hitched at a coupling metal piece 20 of the inner frame 3. The legs 24, 24 of the spring member 22 are deformed elastically, and the tips of these legs are inserted to the inside of the first louver plate 4a having approx. V-form cross-section. The elastic deformations of the legs 24, 24 are disengaged, and the hitching parts 25, 25 at the leg tips are detained with the detention hole 10 from the inside, and the inner frame 3 is installed on the mounting hole 13 in the louver body 5 so that the body 1 of a light control device is formed.