To clarify the role of dopants on the reduction rate of hematite with hydrogen, the losses in weight have been measured for pure and doped hematite. Sodium oxide, magnesium oxide and calcium oxide were used as dopants. The ionic radii of these dopants were larger than that of hematite. The reduction rate of the doped hematite was increased with increasing radius of dopant. However, the reduction rate was not concerned with the radius of dopant when solid solution was formed between dopant and hematite. The role of dopants on the reduction rate were discussed in terms of defect structure of hematite and electron transfer mechanism. When a dopant incorporated in hematite expells the interstitial Fe²⁺ ions to the octahedral position, the structure of the doped hematite turned out to be more defective than that of a normal hematite, and the rate of reduction was increased. When a dopant expels the octahedral Fe²⁺ ions to the interstitial position, the structure of the doped hematite became nearer to the stoichiometric structure than a normal hematite, and the rate of reduction was decreased.