These days, the space-borne SAR becomes one of the powerful instruments to observe the earth surface. On the other hand, a airborne SAR is also important for development of SAR system and analysis technique. Moreover, airborne SAR is able to make immediate observation of disaster area. The National Institute of Information and Communications Technology (NICT) has been developing the new airborne synthetic aperture radar: PÍ-SAR2 since 2006. The PÍ-SAR2 is an airborne X-band polarimetric and cross-track inter-ferometric SAR with sub-meter spatial resolution. The spatial resolution is measured less than 0.5m using some corner reflectors. The PÍ-SAR2 system were completed and began the operation in autumn 2008.