In this paper, the author conducted a comparative study of the way in which expansion of lowuse or unused land affects the spatial structures of Matsuyama and Takamatsu cities, in order to clarify the mechanisms of "land disuse" in CBD of regional centers, and at the same time to seek out directions for reorganization of land use in the future. As a result of this study, we found that there has been a gradual formation of a urban structure exhibiting a bipolar decomposition in both cities, comprising i) a dense concentration of functions along major roadways, and ii) a shift toward land disuse in inner city blocks. Another characteristic common finding to both cities was a rapid transition in land use from low-use or unused land along major roadways, and a comparatively slow land use change in inner city blocks. Possible reasons for these trends are the decrease in low-use or unused land along major roadways, and the establishment of new small parking lots (or the expansion of existing parking lots) in inner city blocks. Furthermore, in Takamatsu city, unlike Matsuyama city, there is a slow transition in land use from low-use or unused land, and the increase in unoccupied buildings in particular is promoting a degeneration of urban areas. This trend is a significant factor in defining the urban structure in both cities. In Takamatsu city, the effective use of low-use or unused land, combined with reorganization of high intensive build area and a revitalization of industry, is an urgent issue.