Engineering and meteorological feasibilities of a circum-south-polar ballooning project, called ``Polar Patrol Balloon (PPB)'', for space and geophysical researches are studied. We plan to use zero-pressure balloons mounting an auto-ballasting system, utilizing the non-sunset condition in mid-summer. PPB will be launced to a level higher than 30 km from an observational base in the Antarctica and come back there by a circumpolar wind. It is predicted that the circumpolar period may be a few weeks in the case of mid-summer 30 km-level flight and its meridional deviation after a circumpolar flight may be within a few hundreds kilometers. We have tested auto-ballasting and ARGOS-tracking, and are developing some on-board data accumulation systems and power supply. If we can collaborate with foreign bases, results of PPB should be much more successful especially concerning simultaneous observations at various latitudes.S. Ohta, T. Yamagami, M.D. Yamanaka (ISAS); S. Kawaguchi, H. Yamagishi, H. Kanzawa, H. Miyaoka, R. Fujii, F. Nishio (NIPR); T. Kamata (Nagoya University); S. Kokubun (University of Tokyo); and M. Kano (Japan Meteorological Agency).