A recent status and future prospect of nucleon decay experiments are summarized. The most stringent limits on proton decays are given by the largest water Cerenkov detector, Super-Kamiokande. A lower limit on the partial lifetime of a proton is set at 5.4 × 1033 years for p → e+π0 at 90% C.L., and 2.2 × 1033 years for p → ν ¯ K + . A next generation experiment with a megaton mass-scale detector can improve the sensitivities up to 1035 years for p → eπ0 and 1034 years for p → ν ¯ K + . The detector is also suitable as a far detector of a long baseline neutrino oscillation experiment to search for CP violation.