The deep water ( 1000-3000 m) circulation in the area east of Taiwan and the Philippines has been little studied . Moriyasu (1972) and Reid (1981) discussed the 3000 db surface (3000/1200 db ) and 2000 db surface (2000/3500 db ) circulations of the Philippine Sea Basin .respectively . They both showed that there may be a northward current close to the western margin of the Sea Basin . Recent analyses of two sets of deep sea hydrographic data yielded quite different results, i. e ., at deep waters in the area east of Taiwan and the Philippines southward countercurrents flow under the upper northward currents .The possible causative mechanism of these southward deep countercurrents is the blocking effects of the submarine ridge east of Suao and of the Ryukyu Islands Shelf on the northward flowing upper currents .The above-mentioned preliminary deductions were wholely based on consideration of the relative geostrophic current and calculation, though the reference surface (3500 db ) was very deep . It is su The deep water (1000-3000 m) circulation in the area east of Taiwan and the Philippines has been studied. Moriyasu (1972) and Reid (1981) discussed the 3000 db surface (3000/1200 db) and 2000 db surface / 3500 db) circulations of the Philippine Sea Basin. In perspective. They all be shown that there may be a northward current close to the western margin of the Sea Basin. Recent studies of the sets of deep sea hydrographic data yielded quite different results, i. e., at deep waters in the area east of Taiwan and the Philippines southward countercurrents flow under the upper northward currents. may possible causative mechanism of these southward deep countercurrents is the blocking effects of the submarine ridge east of Suao and of the Ryukyu Islands Shelf on the northward flowing upper currents. above-mentioned preliminary deductions were wholely based on consideration of the relative geostrophic current and calculation, though the reference surface (3500 db) was ve ry deep. It is su