||As the city is commercialized, the number of stores is increased and it also makes outdoor billboardsâ number increased accordingly. And signboards on the street make pedestrians unpleasant, making light pollution by light reflection. In this study, we measured the luminance to target the outdoor signboards of commercial area in Seoul. On the basis of the obtained results, the External system showed high luminance values, and the luminance values of Letter-type system were lower. Furthermore, the measured value at the midnight time was higher, and we considered that the more floating population bring about the high luminance value of the External system. The signboards of External system should be avoided, the Letter-type system should be recommended.