In order to investigate the characteristics (or the sources) of Precipitations in Niigata Prefecture, oxygen stable isotopic ratios (i.e., δ18O) and the concentrations of rare earth elements (REEs), thorium (Th), and uranium (U) in the precipitation samples were measured. The precipitation samples were collected using a filtrating bulk sampler every two weeks at 3 points in Niigata Prefecture during the period from December 2003 to December 2004. Consequently, the following matters have been mainly clarified. (1) In rainy season, δ18O value of Precipitations was the smallest. (2) In regard to δ18O value, “Continental effect” and “Amount effect” was generally observed in this work. On the other hand, “Temperature effect” was remarkably found only in winter. (3) The concentrations of trace metallic elements (REEs, Th, U) increased in spring. (4) REEs in precipitations might have been derived from a crustal source as well as oceanic source, while anthropogenic source was not negligible.