K physics at KEK with the present 12-GeV and future 50-GeV PS

The current status of the two K-decay experiments, which are now underway with the 12-GeV proton synchrotron (PS) at KEK, is reported. One is to detect a rare decay mode K_L → π⁺π^-e⁺e^-, and the other to search for the T-violation in the K⁺ → π⁰μ⁺ν decay. Some comments are also given on possible K-decay experiments with a high-intensity 50-GeV PS, which is proposed to build in the near future at KEK.