The purpose of this paper is to analyze spatial patterns of interregional trades and their changes by stages of distribution routes and by industries in Japan.<br>The data were obtained from the statistics concerning the inter-regional trades in the Census of Commerce. The statistics are composed of two substatistics: one shows total sales in wholesaling and retailing for one year by prefectures, industries, and buying sources (the table for buying sources). The other shows total sales in ones by prefectures, industries, and selling destinations (the table for selling destinations).<br>Five categories of industries were chosen for the objects of analysis; all wholesale, agricultural product wholesale, clothing and apparel wholesale, machinery and equipment wholesale, and all retail. These three subdivided groups of wholesale were chosen with the assumption that the spatial pattern of distribution of some goods largely depends upon the form and spatial distribution of their production and consumption. That is, agricultural products are dispersedly produced and consumed to a small amount in respective areas, while machines and equipments are concentratedly produced to a great amount. Clothes and apparels are medium in characteristics between the agricultural products and the machines and equipments in the form and spatial distribution of the production and consumption (Table 1).<br>The years of analysis are 1960 (1962), 1966, 1968 and 1972. The years chosen are based upon the availability of data and changes of industrial classification in the Census of Commerce.<br>The procedure of analysis is as follows: firstly, values of each table of buying sources and table of selling destinations of industries chosen are divided by summation of respective total sales (excluding sales of unknown buying sources or selling destinations) for one year in the table of buying sources and table of selling destinations; secondly, 150 values are selected in order of magnitude of ratios of the values thus divided to identify the main trade routes from each table for buying sources and selling destinations; thirdly, the values selected are arranged to the format of O-D matrix (origin-destination matrix) and then mapped; forthly, quantities of changes of the above O-D matrices between the years are calculated. The changes of spatial pattern are discussed by means of mapping of the quantities thus calculated.<br>The findings are summarized as follows:<br>1) The two types of inter-regional trades are distinguished at the stage of buying by wholesalers (Fig. 2, Fig. 5); one is the region-wide trades which form regional trade areas, the eastern Japan with Tokyo as the buying center, Tokai district with Aichi, the western Japan (excluding Kyushu districct) with Osaka, and Kyushu district with Fukuoka; the other type of the inter-regional trades is the nation-wide trades mainly composed of trades between metropolitan prefectures. Trades among the three largest metropolitan prefectures (Tokyo, Osaka and Aichi) are characterized by the large volume of trades of each of those prefectures and between every set of the two prefectures. The trades between the three largest metropolitan prefectures and prefectures with regional capitals (Hokkaido, Miyagi, Hiroshima, Kagawa, and Fukuoka) are characterized by the one-direction of buying from the metropolitan prefectures to the latter prefectures. This fact indicates that regional capitals have some functions as the relaying centers in trades (Sapporo in Hokkaido, Sendai in Miyagi, Hiroshima in Hiroshima, Takamatsu in Kagawa, and Fukuoka in Fukuoka).<br>2) As for the stage of selling by wholesalers, seven selling areas are distinguished; Tohoku district as selling area of Miyagi, Kanto district of Tokyo, Tokai district of Aichi, Kinki district of Osaka, Chugoku district of Hiroshima, Shikoku district of Kagawa, and Kyushu district of Fukuoka (Fig. 3, Fig. 6).