This presentation introduces the analysis of the bottom hole pressure data acquired in the CO2 sequestration project done as part of “Research and Development of Underground Storage Technology for Carbon Dioxide” that the Research Institute of Innovative Technology for the Earth (RITE) executed from 2000 to 2006. The bottom hole pressure gauges observed over 30 times of pressure fall off curve caused by the shut-in due to the surface facility's trouble. From the transient analysis of this sequence of fall off curves, the improvement of injectivity which is expected to result from vaporization of formation water into dry injected CO2 was observed as well as the expansion of CO2 distribution.