The Kokufu was built in the 7th century as the results of old Japanese bureaucracy. They were the center cities in old Japanese local countries “Kuni”, but their forms and scales are not so clear now. The only exact relics which had been researched till now are the Kokufu of old Suo country (modern Yamaguchi prefecture). Its scale is measured about 1 square km and in the raids of it there were the central office buildings of Kokucho and the main street run from the north to the south. Surrounding the Kokufu there were also banks, moats and four gates.
In this treatise the author tried to explain the geographical characters of all Japanese Kokufu from the next points.
1. The geographical significances of the Kokufu research.
2. On the reconstructions of the Kokufu from the old Japanese do-cuments, place names, etc.
3. On the problems of local site and geographical distribution of the Kokufu.
4. On the forms and structures of Kokufu.
5. On the relations between Kokufu and old roads, old land plann-ing, Jori system of ancient Japan.
The author thinks that the Kokufu was built on the most favourable place such as the center of alluvial delta or inner basin of old coun-tries. Their relative position was also selected as the focus of old politics and communications. Their forms and structure were similar, to old Japanese capitals, such as Heijokyo (old Nara city) or Heian kyo (old Kyoto city), so that we must understand the Kokufu as the bureaucracial local cities of ancient Japan. Some of the forms of the Kokufu were succeeded long after, but their political functions were. destroyed in the next feudal ages. In this treatise the author re-serched especially about the Kokufu of Ise, (Mie prefecture), Echizen, (Fukui prefecture), etc. The former is situated on the diluvial terrace of old Suzuka river. In that relics the author excavated the ancient tiles and reconstructed the city plan of about 1 sq. km. The Kokufu of Echizen which now existed along the Hino river in then Fukui basin and succeeded by modern Takefu city.

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The seismic method is the best way to recognize clearly the under ground structures of alluvial plains. This report shows the results of our investigations on the three alluvial plains as follows:
1. Ofunato plain: This plain is the small delta that was construct ed in the drowned valley. We set 4 lines of measurement as shown in Fig. 1. Fig. 2-3 are the results of this investigation along the lines. The layers, in which the velocity of the longitudinal wave are 5.0 & 5.7km/sec, are palaeozoic and 6.0 & 4.2km/sec are granit. The surface of these rocks is the fossil valley before it drowned. The layer of 2.4 km/sec is the diluvial gravel bed, and the others are alluvial. Under the delta, several faults were discovered.
2. Joganji plain: This is the alluvial fan which was made by River Joganji. Fig. 4-11 are the results. The layers of 2.8, 3.0 and a part of the 2.6km/sec are Tertiary, and the others are the gravel beds. At the middle of the fan, it became clear that a buried hill exsists under the gravel beds, and the ancient river course ran more west than now. E line was set at near the coast, and the altitude of the surface of the bed rock on the east end of the line was 450m high. The old river would run more east and deeper than this point.
3. Upper part of Nobi plain: This part of the plain is the fan made by River Kiso. The positions of the lines and results of the in-vestigation are shown in Fig. 12-14. The layers of 4.5km/sec is ther pre-tertiary rock. The others are all gravel beds from Tertiary to, alluvial. We can read the geological history of this area from these-geological sections.

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[in Japanese]

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