Recently, research has been done from various directions to evaluate the brightness of spaces. However, no studies have been conducted regarding quantitative measurements of the brightness at different positions in a visual field. That is, a model for evaluating the brightness of spaces and lighting design techniques have not been considered much regarding the brightness at different positions in the visual field. Therefore, in this study, the sensitivity to brightness at different positions in the visual field was investigated in order to quantify brightness perception throughout the entire visual field. The experimental results show the tendency for Lm/Lt rises as the visual angle increases. Moreover, they show the Lm/Lt in the vertical lower direction is higher than that in other directions, especially at 20 degrees or more.