The Japanese Antarctic activities have been resumed on the occasion of Japan's participation in the International Geophysical Year, 1957-1958. The 1st Japanese Antarctic Research Expedition (JARE), under Dr. T. NAGATA'S leadership, was organized to establish a scientific station in Antarctica, and was dispatched on board the icestrengthened ship SOYA. In 1957 Syowa Station was established at 69°00'S,39°35/E on Ongul Island, off Soya Coast, Prince Haraid Land. Syowa was temporarily closed between 1962 and 1965, because of the superannuation of the SOYA. During the cessation period, the icebreaker FUJI was built. Operated by the Japan Maritime Self Defence Force, the FUJI was placed in commission and the 7th JARE reactivated Syowa in 1966. Since then, the facilities at the station have been rapidly amplified year by year. The present report outlines scientific and logistic activities of the summer party of the 15th JARE in the Southern Ocean and in the vicinity of Syowa during the period between the departure from Fremantle, Australia on December 16, 1973 and the arrival at Cape Town, South Africa on March 9, 1974, The 15th JARE consisting of 40 men was led by the author. Thirty of the 40 scientists and technicians constituted the wintering party led by Mr. Nozomi MURAKOSHI, deputy leader of the Expedition. The scientific program of the 15th JARE was prepared by the Planning Committee (Chairman, Dr. T. NAGATA) of Polar Research Center, National Science Museum, which was reorganized into the National Institute of Polar Research in September 1973. The program is a part of the long-term yearly plan listed in Table 4, and has been officially approved by the Promoting Headquarters of JARE presided by the Minister of Education. It must be noted here that the environmental science, in connection with biology, human physiology and geochemistry, will be studied at a newly established environmental science laboratory (shown in Fig. 1). Also, the inland survey is to be counted for much by a team of glaciologists, geologist, geophysicists and meteorologists in the Mizuho Gamp, located at 70°42'S, 44°18/E, 2,050 meters above sea level and in the Yamato Mountains. For this purpose, a living hut, accommodating 4 berths (shown in Fig. 2) will be erected in the Mizuho Camp by the wintering party. Inland oversnow traverse, including the trip to the Enderby Land, during the summer of 1974-1975 will resurvey the strain grids which were set by the llth JARE, and will carry out a glaciological study in the field. The inland operation will be supported by an aviation group of one pilot and one mechanic using a single-engined monoplane, Cessna 185. These two projects take place of the sounding rocket observations made at Syowa by the 12th, 13th and 14th JARE wintering parties. On the other hand, the research programs assingned to the summer party are centered on a preliminary investigation for the study of environmental science to be carried out at Syowa and its vicinity by the wintering party, as well as on oceanographical observations to collect data of marine environment around Syowa. The expenses of the 15th JARE were defrayed mostly from the budget for the 1973 fiscal year (April 1, 1973 to March 31, 1974). The allocated amount was US$ million 4.169, to cover the following expenditure: (1) Science programs, US$ million 1.359 comprising the expenses for scientific research (0.524), logistics (0.579), personal expenditure (0.244) and training expenditure (0.012). (2) Operation of the FUJI, US$ million 2.741, comprising the expenses for repairs (1.026), purchase of a helicopter (0.686) and general expenses (1.029). (3) The Promoting Headquarters expenditures, US$ million 0.069. The Promoting Headquarters, for the first time, sent out a representative to the 15th JARE as an observer. Dr. Kiyoo WADACHI, expresident of the National Antarctic Committee of the Science Council of Japan and ex-director of Japan Meteorological Agency, joined the summer party aboard the FUJI from Tokyo to Cape Town, as was the case of the exchange scientist Dr. Norberto Luis BIENATI, Scientific Department of National Antarctic Research Institute, Ministry of Defence, Argentina. The mission of the summer party comprises three tasks, that is, oceanographical observation aboard the FUJI during the cruise from Fremantle to Cape Town, survey and research work in the vicinity of Syowa in austral summer, and logistic support for the 15th wintering party. Leaving Fremantle on December 16, 1973, the FUJI moored at the edge of fast ice, approximately 27 nautical miles NW of Syowa, on December 31, 1973. The author observed that, due to the long spell of fine weather from November 8 to 25, sea ice of this area had been loosened and swept away beyond expectation in comparison with the ice conditions in the previous two or three years. In addition, although the Syowa area was visited by blizzards on November 28, December 8 and 20, they were all weak and lasted only one day, without deteriorating the condition of pack ice in Liitzow-Holm Bay. Figure 3 shows the route of the FUJI and ice conditions in the period from December 1973 to February 1974. Shuttle flights of helicopters were made immediately to transport men and cargos from the ship to Syowa. At the same time, surface transportation of KD60-type inland oversnow vehicle, No. 609, which had failed to be landed in the last three years, was carried out before the fast ice became loose. Figure 4 shows the transportation route on fast ice from the FUJI to Syowa. About 500 tons of cargos were transported by air and surface. The breakdown of the cargos is as follows, with weight in ton in paren theses: Scientific equipments (39.5), Machines and vehicles (55.0), Fuel (313.0), Construction materials (42.5), Foods (34.0), Others (10.0), Total 494.0 tons. The environmental science laboratory, accommodating a bacteria cultivation room, a chemical work room and a measurement room, was erected. A tank containing 10m^3 hydrogen for weather balloons, was installed together with a generator connected to the balloon-inflating hut. On February 1, 1974, scientists of the 15th JARE took charge of routine observations of weather, ionospheric sounding, geomagnetism, seismology, and tide observation at Syowa. The inland traverse party of the 14th JARE who traveled from the Yamato Mountains joined the members of the 15th at the Mizuho Camp where a direction finder for Cessna flight was installed by the latter. The former reached the depot on the continent, from where the party evacuated by helicopters on February 5. Meanwhile, several groups of biologists and geochemists were sent to the area of exposed rocks and saline lakes for studying biology, ecology and geochemistry. At the same time, ground control surveys were conducted for map compilation. As the station was actually taken over by the 15th wintering party on February 1, 1974, the 15th summer party hastened back to the FUJI on the early morning of February 6, after picking up the 14th JARE personnel. From that time on, the summer activity was focussed on the oceanographycal observations in the Southern Ocean between Lutzow-Holm Bay and Cape Town (Table 14 and Fig. 10). En route to Cape Town the FUJI visited Molodezhnaya Station, USSR, (67°50'S, 45°50'E) on February 12. The author, Captain M. MORITA of the FUJI, Dr. WADACHI and others were welcomed by Dr. P. K. SENKO, leader of the 18th Soviet Antarctic Expedition, who personally guided the author throughout the Station. Dr. SENKO and his men paid a visit to the FUJI by helicopters and a mutual welcome party was held. The FUJI continued the survey cruise as shown in Fig. 10 and on February 27, 1974, at the point of 66°27'S, 01°40'E, she changed her course northward for home via Cape Town.