<p>Nutrients distributed in the surface layer in winter are an important source of phytoplankton bloom in spring. To understand nutrient dynamics in winter, nutrient distributions were examined based on observations from eight survey cruises (2004–2016) in the northern East China Sea (NECS). By analyzing data from these cruises along with data from seven winter cruises (1988–1996) by the Japan Meteorological Agency, interannual variabilities and trends of nutrient distributions were assessed. Within the studied area, a water mass with high temperature and high salinity was distributed in the east and another water mass with low temperature and low salinity was in the west. Nitrate + nitrite (NOx) and dissolved inorganic phosphorus (DIP) concentrations were negatively correlated with temperature, showing that sea surface cooling in winter plays an important role in the supply of nutrients to the surface layer in the eastern part. Both of these concentrations fluctuated with interannual variations in sea surface temperature. In the western part, although NOx concentrations showed an increasing trend over time, DIP concentrations did not, suggesting nitrogen input from anthropogenic sources in this region. Consequently, the NOx/DIP ratio increased up to 21 in the western part. Data from 15 winter cruises showed that the mechanisms of nutrient supply to the surface layer are clearly different between the east and west of the NECS.</p>