PURPOSE: To surely control raw material grain size distribution in radius direction of a blast furnace by utilizing natural classification piling surface in an upper step hopper and raw material discharging characteristic, classifying the raw material into each grain size during operation and improving the raw material discharging characteristic.

CONSTITUTION: In the lower step hopper 5 in a single port system center feed type bell-less furnace top charging apparatus, setting the raw material hopper at upper and lower two steps, at least a double hollow cylindrical shaped partition walls 13a, 13b and a scattering prevention plate 13c as changable to inclination at the upper part thereof, are arranged. After charging and packing the raw material having different grain sizes into the cylindrical partition wall 13a at central part from the upper step hopper 2, this is hit to the scattering prevention plate 13c with overflow and packed into the adjoining space of cylindrical partition wall 13a in order. As the other way, the raw material is packed into the adjoining space at the same time so as not to hit the overflow raw material by changing angle of the scattering prevention plate 13c, and by opening a lower gate, variation the grain size of raw material with the lapse of time at in the time of charging this into the furnace is made to 'monotonous increasing pattern'.