Mineral assemblage in the deep interior of the giant planet such as Super Earth is the challenging subject for the experimental study because of the significant difference between experimentally producible pressure and real pressure at the interior of the giant planet. One of the plausible ways is an approach from the analogue material, and then titanate is expected to behave as analogue of silicate even at low pressure. Although the long-held expectation was the decomposition of ABO₃-type compound into AO+BO₂ assemblage at the ultrahigh pressure, present experimental work showed that 2/3AO+1/3AB₃O₇ assemblage is the densest and this model may be more stable at deeper interior of the giant planet. Experimental study also found Th₂S₃-type structure in Ti₂O₃ which structure corresponds to post-postperovskite phase. The dense assemblage and phases found in titanate are promising for investigating the behavior of silicate under ultrahigh pressure such as the deep interior of the giant planet, super earth.