We propose a method for segmentation of written regions on a blackboard in the lecture room using a video image. We firstly detect static edges of which locations on the image are stationary. Next, we extract several rectangular regions in which these static edges are located densely. Finally, by use of fuzzy rules, extracted rectangles are merged as contextual regions, where letters and figures in each contextual region explain each context. In addition, we apply our method to automatic production of lecture video, and archives system of written regions on the blackboard in lecture rooms.