Studies of Japanese medieval cities have been interdisciplinary, including the fields of history, archaeology, architectural history, and geography. The central issue of the studies has been how to reconstruct and explain the "space" of the cities, but the strict meaning of the key concept "spatial structure" has never been explored. However, current studies have arrived at the point of reassessing their perspectives and methods of spatial analysis from their own academic points of view. This paper aims to review the studies of Japanese medieval cities by examining the meaning of the spatial structure and perspectives on spatial analysis. Prior to the 1970s, historians had displayed a strong interest in the late-medieval castle towns, which were seen as immature feudal cities on the verge of developing into the consummate feudal cities of early-modern times. They determined the locations of the castle, residences of the warriors, and markets in each city, and they used this data as a standard to estimate the level of development as a feudal city. They understood the "spatial structure" as the relative connection of the locations of these three elements. In the late 1970s, influential papers were published by the historian Amino Yoshihiko, who defined the space where people engaged in various economic activities free from the intervention of a feudal lord as an "urban location" During the same period, archaeological surveys produced many remarkable results, especially on some early medieval cities. The conceptual term urban location was reconstructed in actual spatial form by a group of historians and archaeologists working together who used the many actual excavations of early-medieval sites. Because this method of reconstruction was used to make up for the lack of space where archaeological surveys had not been conducted, the abstract model of the center and periphery was applied to the entire urban space. This method caused confusion between abstract and concrete spatial structures when using the term urban location. On the other hand, other historians and archaeologists joined to initiate the study of the changes in castle towns from late medieval to early modern times, but in manner divorced from the older theories about feudal cities. They found the medieval castle towns had two different varieties of space. One type of space was under the control of powerful lords, and the other type was space that was free to a certain extent from the power of the lords. They claimed such multivalent space was unified by the powerful lords in early modern times. Their dynamic but linear view of the development of the history of castle towns had a great influence on many researchers. Furthermore, their method of reconstructing space that clarified the concrete morphology and function of urban elements of the city as a whole was also widely accepted. The space reconstructed by this method was recognized as the spatial structure of the city. In the 1990s, an architectural historian presented a remarkable model to explain the history of the space of the Japanese cities from ancient through modern times. That model, composed of two symbolic factors, was exceedingly abstract. It succeeded in explaining the multiple and complex space of medieval cities in their totality. In other words, this meant that the spatial structure of the city was a model that was symbolic and highly abstract. As is demonstrated in this paper, studies of Japanese medieval cities have not shared a common understanding of the most important concept of spatial structure, so researchers have employed perspectives appropriate to their own themes in analyzing space. Due to the confusion borne of a lack of recognition of the concepts of space and spatial structure, researchers have faced problems in exchanging results of studies with each other. The fundamental cause of this problem lies in the attitudes of most researchers who have not paid serious attention to space itself