Discovery of Neutrino Oscillation by Super-Kamiokande

At the Neutrino 98 Conference in Takayama, Japan, Super-Kamiokande collaboration announced an evidence of neutrino oscillation observed in atmospheric neutrinos. The discovery indicated that neutrinos has mass and their flavours mixes, which was beyond the standard model which assumed neutrinos to be massless. The discovery followed by an era of series of neutrino oscillation measurements. Prof. Takaaki Kajita received~ Nobel prize with Art McDonald for the discovery of neutrino oscillation last year. In this talk,~ I will review this discovery measurement, in particular how the collaboration was convinced that the neutrino oscillation exists under significant uncertainties in atmospheric neutrino flux and their interaction cross sections.