[en] Since the project on next generation linear collider (LC) was proposed in the middle of 1980s, great progress on it had been made. R and D on LC structure are described. Various structures to suppress the long-range wake field within a train of bunches were suggested. And two kinds of them remain to be the actual candidates. One is 'damped structure' and the other is 'detuned structure'. The current status on LC structure at SLAC and KEK are also described