The KEK electron/positron injector linac is supplying 8 GeV electron beams to the KEKB high-energy ring and 3.5 GeV positron beams to the low-energy ring, as well as 2.5 GeV electron beams to the PF and PF-AR rings. This linac comprises a special accelerator module that includes a bunching section and 56 regular accelerator modules, each involves a 40 MW rf source with SLED and four 2-m accelerator sections operated at 2856 MHz. The operation time of the KEKB linac will amount to 7200 hours for fiscal year 2000 because of the heavy competition with the PEPB. More than 100 50-MW klystrons have been produced. Their average life time and MTBF value reached 13500 and 70500 hours, respectively, which shows an affirmative insight into achieving a desirable average life time of 30000 hours.Presenting Author : Shidara T.