Recent advance in high-pressure technique has enabled us to reach a pressure of a few hundreds gigapascals with a diamond anvil cell. At such extremely high pressures, materials are highly compressed and exhibit various novel characters which can not be realized under ambient condition. A diffractometer installed at the second station of BL10XU was designed and constructed for polycrystalline x-ray diffraction measurement at ultrahigh pressures. Recent research activities at this station are described and a future perspective of ultrahigh-pressure synchrotron radiation science is briefly discussed.