[en] Various experiments using the 12 GeV proton accelerator at KEK have been made since 1977. The construction of the accelerator was completed in December, 1976. The accelerator consists of a 750 keV Cockcroft-Walton machine, a 20 MeV proton linear accelerator, a 500 MeV booster synchrotron, and a 12 GeV synchrotron. Some experiments were made, using the facility annexed to the booster machine. The facilities at the 12 GeV synchrotron are the fast extraction beam facility, the internal target beam facility, the slow extraction beam facility, and the external target beam facility. KEK 1 m liquid hydrogen bubble chamber was constructed, and is used for experiments. The counter experiments performed at KEK are π-meson-nucleon scattering experiments, exotic resonance experiments, and the experiments on electromagnetic and weak interactions. The bubble chamber was used for the experiments on inclusive reactions, the mass spectra of π-meson-nucleon system, the energy dependence of the pair production of leptons, and the multiplicity of π mesons and scaling. The study of nuclear physics using high energy protons and mesons has been developed at KEK. Spallation reaction, high energy nuclear reaction, neutrons associated with high energy reactions, π meson absorption cross-section, the angular momentum effect in meson absorption process, the production of compound particles, and the bubble chamber experiment with nuclear targets have been studied. (Kato, T.)