This paper is the study on the structure of Ikebukuro busy quarter which is one of the busy quarters of Tokyo such as Ginza, Shinjuku, and Shibuya, and Asakusa. This study was done from March, 1964 to January, 1965. The survey was made for all shops and establishments, and also flow of pedestrians in the Ikebukuro area was analyzed, together with some other geographic considerations.<br> The outline of this study consists of the following three parts:<br>(1) Calculation of quantity and ratio of the “busy-quarter” shops and establisments in Ikebukuro busy quarter. Busy quarter of Ikebukure is supported by some 2.5 million people as in the case of Shinjuke, the largest sub-senter of this great metropolis, but Ikebukuro's “busy ratio” is lower than thet of Shinjuku. that is, there are not so many high-class specialty shops here as in Shinjuku. In Ikebukure, the ratio of the establishments selling personal ornaments and rend ering eating and drinking service to that of banks and offices is also low.<br>(2) Ikebukuro busy quarter is divided into three areas. (a) Core area (inside the circulating road of the busy quarter). (b) Inner area (outside but directly neighboring the circulating road). (c) Outer area (in the environs). These three areas were further subdivided into 26 smaller parts in all, along with analysis of characteristics of each area. After analyzing each part counting 26 in comparison with Shinjuku, the following three points were clarified:<br>A. Development of the circulating road is not mature, hence two semi-circulating roads in actuality.<br>B. Three immature core areas located, however, outside the semi-circulating roads.<br>C. Some inner areas are not directly adjacent to the semi-circulating roads.<br>(3) Characteristics of the arrangement and the structure of Ikebukuro busy quarter.<br>A. The busy quarter develops in concentric form around the station, with its centrally unifying character.<br>B. No significant flow of pedestrians as in the case of. Shinjuku, because establishments inducing a large number of people are too closely located to the station.<br>C. The personal ornaments quarter and the eating and drinking quarter are mutually separated by the station.