Conductivity-temperature-depth data from the midwinter in 1997 are examined for the presence of the intermediate water in the eastern Japan Basin, in the northern part of the Japan Sea. Three different water masses can be detected with salinity extrema at intermediate depths between the main pycnocline and the upper portion of the Japan Sea Proper Water (UJSPW). The shallower salinity maximum and the middle salinity minimum can be identified as the Tsushima Warm Current Water (TWCW) and Japan Sea Intermediate Water, respectively. The deeper salinity maximum water, with high temperature and high dissolved oxygen, is identified as High-Salinity Intermediate Water (HSIW) and has density similar to UJSPW (27.30--27.33 &sgr;&thgr;). Isopycnal analyses indicate that HSIW flows southeastward from the Siberian coast, where TWCW outcrops and has an opportunity to become denser by direct cooling. We conclude that TWCW is the origin of HSIW, which in turn, is a source for UJSPW. ¿ 2001 American Geophysical Union