[en] In KEK, TRISTAN electron positron colliding ring has been operated at the energy of 26 GeV by using normal conducting cavities, which were installed in three of four RF sections of Main Ring (MR). For upgrading the energy to 33 GeV, thirty-two superconducting 5-cell cavities are to be installed in the last RF section and construction has been started. For this purpose development of 500 MHz superconducting cavity has been continued in KEK since 1979, the first multi-cell cavity was built and tested in TRISTAN Accumulation Ring (AR). The 5-cell cavities were followed since 1985. Recent efforts are concentrated on establishing the simple and reliable fabrication method of the cavity which has the Q-value of 2 x 10⁹ at the field level of 5 MV/m. Four cavities have already been constructed and tested in a vertical cryostat. Two of them are fabricated for the beam test in TRISTAN Accumulation Ring (AR) scheduled in this October. The others are the first couple of cavities for MR. The results of these cavities are reported in this paper. 8 references, 10 figures, 5 tables