We report here new data on pressure dependence of Fe-Mg partitioning between (Mg, Fe)SiO3 perovskite (Pv) and magnesiow¿stite (Mw), KPv/Mw, and (Mg, Fe)SiO3 post-perovskite (PPv) and Mw, KPPv/Mw, up to 123.6 GPa at 1600 K measured by synchrotron X-ray diffraction method and analytical transmission electron microscopy (ATEM). We observed a high FeO content in PPv coexisting with Mw <KPPv/Mw = (FeO/MgO)PPv/(FeO/MgO)Mw = 0.30> compared to that in Pv <KPv/Mw = (FeO/MgO)Pv/(FeO/MgO)Mw = 0.12> observed from 23.0 to 95.4 GPa. KPv/Mw keeps a constant value of 0.12 up to the PPv phase boundary. Our results also support the possibility that a metallic phase may form in the lower mantle. The assemblage of PPv and Mw is 1.5--1.7% denser than the Pv bearing assemblage, which results in a gravitational stabilization of the lowermost mantle.