Speciation analysis of Cr in some environmental waters in Niigata Prefecture was performed by applying size fractionation and ion-exchange methods. Moreover, the concentration of humic substances was also determined for investigating the relationship between the concentration of humic substances and the speciation of Cr in environmental waters. The experiments yielded the following results: (1) Roughly 50-80 % of total Cr is present in the “dissolved” in normal weather condition. (2) In case of lagoon water samples, the distribution percentage of Cr in the “suspended” (the fraction left on 0.45μm filter when filtrating sample water) or “colloidal” (the fraction left on 0.1μm filter, although passing through 0.45μm filter) is generally large compared to that of river water samples. (3) For all of the investigated water samples, the concentration of Cr (III) species is higher than that of Cr (VI) species. (4) The concentration of total Cr and the distribution percentage of “suspended” remarkably increases after rainfall event. (5) The order of the amount of humic substances in Sakata is LS1 (downstream point of Lower Lagoon (Shitakata)) › LS2 (conflux point of Lower Lagoon (Shitakata) and Upper Lagoon (Uwakata)) ›LS3 (spring water at shore of south area in Lower Lagoon (Shitakata)); and the average concentration of humic substances is about 10ppm.