Crab cavities have been installed in the KEKB B- Factory rings to compensate the crossing angle at the col- lision point and thus increase luminosity. The beam opera- tion with crab crossing has been done since February 2007. This is the first experience with such cavities in colliders or storage rings. The crab cavities have been working without serious issues. While higher specific luminosity than the geometrical gain has been achieved, further study is neces- sary and under way to reach the prediction of simulation.
