To provide a method, by which piling condition of charged material in a blast furnace is simply and continuously estimated by a layer thickness in the radial direction of the furnace in a short time.

After executing the following three processes, i.e., a process for measuring temp. variation ΔTr at the furnace top just before and just after charging the charged material into the blast furnace, a process for measuring temp. distribution (T0i) and gas flowing velocity (u0i) just before charging and the temp. distribution (T1i) and gas flowing velocity distribution (u1i) just after charging at plural positions of the radial direction at the furnace top and a process for assuming the layer thickness distribution at the same plural positions as the radial direction of the furnace to the charged material, the distributing data just after charging is compared with the distributing data just before charging. When both data are different, the above process is corrected and the operation is repeated, and when both data are not different, an estimating value of lower degree ΔTs of the furnace top temp. is obtd. based on the temp. variation at each position in the radial direction of the furnace to just before and just after charging, and this value is compared with the above ΔTr, and at the time of coinciding between both data with error within ±1%. it is judged so that the assumed layer thickness distribution is right.