K2K and a next generation neutrino oscillation experiment

Results of K2K and a plan of the next generation long baseline neutrino experiment is described. K2K experiment has confirmed neutrino oscillation in Deltam(2) similar to 3 x 10(-3) eV(2) region by a well controlled accelerator neutrino experiment. As a next step of understanding neutrinos, T2K (Tokai to Kamioka) experiment has been approved. The experiment will use the high intensity neutrino beam from the JPARC(Japan Proton Accelerator Research Complex) 50 GeV proton synchrotron and Super-Kamiokande. An order of magnitude improvement of the sensitivity in the search of v, v, and a high precision measurement of v, disappearance will be the main objectives of the first stage of the experiment. With success in observing v, v, in the first stage, CP violation in the lepton sector can be investigated with a larger water Cherenkov detector (Hyper-Kamiokande) with upgraded PS in the future.