Cleaning effects of pure water containing dissolved oxygen of very low concentration (LDO water) to metallic contaminants on silicon wafer surface were confirmed. To maintain the concentration of the dissolved oxygen in water, experiments were performed in a glove box in which ambience was controlled so as to satisfy Henry's law between the water and the ambient gas. In the experiment using intensionally contaminated wafers, residual metal contaminants except copper on Si-surface decreased from 1014 atoms/cm2 to 1011 atoms/cm2 after the 1ppb hot LDO treatment at boiling point. This effect depended on the concentration of dissolve oxygen, treatment temperature, and rinsing time. Contact angle of the wafer surface increased gradually from about 10 [deg] with decrease in the residual metals and jumped up to about 90 [deg]. when the amount of residual metals reached to minimum. Then absorption peak of Si-O bonds in FT-IR-RAS spectra also disappeared. These results therefore show that hot LDO water removed metal contaminants from the wafer surface with etching of the native oxide.