PURPOSE: To stabilize the quality of sintered ore by regulating the blending ratio between fine and coarse limestone powders each having a prescribed grain size in accordance with the rate of melting of the whole ore so as to prevent a quality change when the blending of ore is changed.

CONSTITUTION: Limestone powder is classified into fine powder contg. ≥50% grains of ≤1mm grain size and coarse powder contg. ≤50% grains of ≤1mm grain size. The blending ratio between the fine and coarse limestone powders is regulated in accordance with the rate of melting of the whole ore, and sintered ore is manufactured. The rate of melting is the volume percentage of ore melted once in a stage for manufacturing sintered ore in a sintered cake.