Realizing stable and highly efficient operation of blast furnace under low reducing agent rate condition is one of the key issues to contribute problems of energy, resources and global warming. Under low reducing agent rate operation, chemical and thermal driving force in the blast furnace is weakened, and it is considered that the capability of recovering the process from the fluctuation is deteriorated. Therefore the probing the state inside the blast furnace by utilizing the information from the various sensors is important. This study focused on the relation between pressure distribution on furnace wall and packing structure inside the furnace. The blast furnace is a packed bed reactor with upward gas flow, thus the pressure generally decreases from the tuyere to the top. Partially inverse pressure distribution is sometimes observed as an instable phenomenon of the furnace. This study proposed a mechanism to produce such pressure distribution with simple structural change in packed bed. When a vacant space is formed in the packed bed, the gas flow concentrates to this space and the gas velocity increases. At the downstream end of the space, the gas velocity decreases and generates dynamic pressure. This increase of the pressure forms the inverse pressure distribution. In this study, this mechanism was confirmed through experimental and numerical approaches.