3-D ionospheric tomography by using measurements of ground GNSS networks is a powerful tool to investigate ionospheric behavior. Recently, a real-Time 3-D ionosphere tomography system has been developed  to reconstruct 3-D ionospheric density profiles over Japan. 3-D ionospheric density profiles over Japan estimated by a real-Time 3-D tomography system, which is available from March 2016 were used to generate ionospheric correction for single-frequency stand-Alone positioning. On both magnetic quiet and disturbed days (14 November 2017 and 25 October 2017, respectively), stand-Alone positioning corrected by real-Time tomography resulted in mean vertical errors equivalent to those of dual-frequency positioning. The RMS vertical errors of stand-Alone positioning corrected by real-Time tomography were better than those of dual-frequency positioning and equivalent to those of uncorrected single-frequency positioning. More analysis on data sets at different location, in different seasons, and in different magnetic conditions are planned. Although there is no specific plan, it is also interesting to apply the same method to other locations where GNSS receiver networks with the similar receiver density as used in this study.