This study is purposed to compare interior luminance of office space equipped with lightshelf for different model scales (1, 1/5, 1/10) and analyze experimental errors to find the effect that model scales have on the precise estimation of lighting performance and their utility. A comparison of a Mock-up model, sized 12.0m(w)x 7.2m(l)x3.7m(h), designed for experimentation of daylighting systems and its 1:5, 1:10 scale model. The sloped type lightshelf system was designed as 10mm transparency sheet glass, tilt angle degree 29°, and total sized 1.28m (interior length 0.88m, exterior length 0.49m). Measurement was conducted at a point viewing the window part from the rear end of outdoor center-line so that window part, ceiling plane, left and right wall plane and floor plane could be measured. It is to be monitored by the Radiant Imaging ProMetric 1400 under clear sky.