We conducted full-depth hydrographic observations in the southwestern region of the Northwest Pacific Basin in September 2004 and November 2005. Deep-circulation currents crossed the observation line between the East Mariana Ridge and the Shatsky Rise, carrying Lower Circumpolar Deep Water westward in the lower deep layer (θ<1.2°C) and Upper Circumpolar Deep Water (UCDW) and North Pacific Deep Water (NPDW) eastward in the upper deep layer (1.3–2.2°C). In the lower deep layer at depths greater than approximately 3500m, the eastern branch current of the deep circulation was located south of the Shatsky Rise at 30°24′–30°59′N with volume transport of 3.9Sv (1Sv=10 6 m 3 s −1 ) in 2004 and at 30°06′–31°15′N with 1.6Sv in 2005. The western branch current of the deep circulation was located north of the Ogasawara Plateau at 26°27′–27°03′N with almost 2.1Sv in 2004 and at 26°27′–26°45′N with 2.7Sv in 2005. Integrating past and present results, volume transport southwest of the Shatsky Rise is concluded to be a little less than 4Sv for the eastern branch current and a little more than 2Sv for the western branch current. In the upper deep layer at depths of approximately 2000–3500m, UCDW and NPDW, characterized by high and low dissolved oxygen, respectively, were carried eastward at the observation line by the return flow of the deep circulation composing meridional overturning circulation. UCDW was confined between the East Mariana Ridge and the Ogasawara Plateau (22°03′–25°33′N) in 2004, whereas it extended to 26°45′N north of the Ogasawara Plateau in 2005. NPDW existed over the foot and slope of the Shatsky Rise from 29°48′N in 2004 and 30°06′N in 2005 to at least 32°30′N at the top of the Shatsky Rise. Volume transport of UCDW was estimated to be 4.6Sv in 2004, whereas that of NPDW was 1.4Sv in 2004 and 2.6Sv in 2005, although the values for NPDW may be slightly underestimated, because they do not include the component north of the top of the Shatsky Rise. Volume transport of UCDW and NPDW southwest of the Shatsky Rise is concluded to be approximately 5 and 3Sv, respectively. The pathways of UCDW and NPDW are new findings and suggest a correction for the past view of the deep circulation in the Pacific Ocean.