KEKB/SuperKEKB injector experience Kazuro Furukawa, KEK KEK injector linac has injected electrons and positrons for particle physics and photon science experiments for more than 30 years. In the previous KEKB project, full energy injection with enough amounts of 8-GeV electron and 3.5-GeV positron was one of the challenges at that time. We could achieve the designed beams and contributed to the world highest luminosity record in the collider ring. There were many ideas realized during the project, including beam stabilization, two bunches in a pulse, channeling enhanced positron, quasi-simultaneous (pulse-to-pulse modulated) injection, and so on. It has been upgraded towards the SuperKEKB project, which aims at a 40-fold increase in luminosity over KEKB, in order to increase our understanding of new physics beyond the standard model of elementary particle physics. SuperKEKB asymmetric electron/positron collider with its extremely high luminosity requires a low emittance and low energy spread injection beams from the injector. Electron beams will be generated by a new type of RF gun, that will provide a much higher beam current to enable a large stored beam current and a short lifetime in the ring. The positron source is another major challenge that enhances the positron bunch intensity from 1 to 4 nC by increasing the positron capture efficiency, and the positron beam emittance is reduced from 2000 ƒÊm to 20 ƒÊm in the horizontal plane by introducing a damping ring, followed by the energy compressor and bunch compressor. Some of those experiences of design, construction and operation in KEKB and SuperKEKB projects will be reported.