The mission of Advanced X-ray Laser Laboratory is to upgrade the light source performance of SACLA (XFEL: X-ray free electron laser facility) and SPring-8 (large-scale SR: synchrotron radiation facility), which are in operation in RIKEN SPring-8 Center (RSC). We are developing magnetic devices called undulators, which produce intense X-ray laser and highly brilliant SR by deflecting the high energy electron beam. We also explore more advanced XFEL and SR concepts that will open up a new possibility of X-ray science. By promoting these R&Ds, we pursue the goal of enhancing the light source performances of SACLA and SPring-8, and establish an “ultimate X-ray laser facility” in RSC, which eventually leads to creation of a new field of photon science exploiting X-ray lasers.