When the visual environments are to be evaluated correctly the most essential point to bring conditions of evaluation close to worker's acutual situation is to introduce the movement of worker's sight line and the ensuing change of his adaptation luminance in conditions. To realize above, authors have been studying the dynamic evaluation of the visual environment and this paper is a part of it's program. Authors have suggested the method of the dynamic evaluation for discomfort glare after clearing the irrationality of the conventional assumptions that worker's sight line is always fixed and his eye always perfectly adapted to the luminance of his visual field. First, in the case of uniform luminance field, the evaluations of discomfort glare obtained by three subjects under both perfectly adapted condition and transition stage of adaptation are compared and discussed. The results make it clear that there are striking differences in discomfort glare sensations between both conditions of which luminances are equal. Authors propose the method to evaluate discomfort glare dynamically from three factors which are pre-adaptation luminance (L_1), the field luminance to be evaluated (L_2) and the time after the luminance change from L_1 to L_2 (T). Secondly, the method to deal with non-uniform field is investigated and the figures are proposed which give the luminance of the equivalent uniform field to the single glare source on the sight line as to the discomfort glare. Using two figures in combination, it can be obtained the worker's dynamic discomfort glare sensetion which he really feels, when he moves his sight line from his working planes to a glare source. It must be noted that the figures here presented are based on the data from only three subjects. For the use of practical evaluation, another figures must be prepared using sufficient number of subjects. Finally, referring to our results, the discomfort glare formula presented by Conell University in USA is examined and it's irrationality is pointed out.
