Although Cicuta virosa does not originally accumulate heavy metals, C. virosa that grows in Hitachi mine, which is heavily polluted by heavy metals, accumulates Zn and several heavy metals in the root. Interestingly, C. virosa without endophytes could not accumulate heavy metals, indicating that the presence of endophytes is important for heavy metal accumulation in fine root. Here, we investigated how these endophytes contribute to the accumulation of heavy metals in the root. Endophytic bacteria solubilized heavy metal. However, heavy metal accumulation in fine root could not be described by only the heavy metal solubilization ability. We next, focused on the bacterial extracellular polymeric substances (EPS), which may trap heavy metals. In the result of ICP analysis, EPS absorbed Zn, Cd, Ni and Cu. Further analysis, suggested that extracellular DNA and protein were involved in the heavy metal absorption as well as the polysaccharides which is the main component of EPS. Taken together, the data suggest that endophytes contribute to the heavy metal accumulation of the plant by solubilizing heavy metals and by trapping heavy metals with EPS.