A blast-furnace operating method in which iron-oxide raw material is reduced to obtain molten pig iron by charging the iron-oxide raw material, coke, and partially reduced iron from the furnace top of a blast furnace, and also injecting pulverized coal and oxygen-enriched air from a tuyere of the blast furnace, the blast-furnace operating method comprising: a first step of adjusting a charging rate of the coke while monitoring a furnace-top temperature T top; a second step of adjusting an injection rate of the pulverized coal while monitoring an in-furnace superficial gas velocity u and the furnace-top temperature T top; a third step of adjusting an oxygen-enrichment ratio of the oxygen-enriched air while monitoring a combustion temperature T f at the tuyere and the furnace-top temperature T top; and a fourth step of determining whether an injection rate of the oxygen-enriched air needs to be adjusted, based on a value of the in-furnace superficial gas velocity u, when the charging rate of the partially reduced iron is increased, at the first step, the charging rate of the coke is decreased within a range where the furnace-top temperature T top satisfies the following expression: T top ≥ T topmin wherein in expression, T topmin is a given temperature that is set within a range equal to or lower than 120°C; at the second step, the injection rate of the pulverized coal is increased within ranges where the in-furnace superficial gas velocity u and the furnace-top temperature T top respectively satisfy the following expressions and: u ≤ u max T top ≤ T topmax wherein in expression, u max is a given velocity that is set within a range from 100 to 150 m/min, and in expression, T topmax is a given temperature that is set within a range equal to or higher than 180°C; at the third step, the oxygen-enrichment ratio is increased within a range where the furnace-top temperature T top and the combustion temperature T f respectively satisfy the above expression and the following expression: T f ≤ T fmax wherein in expression, T fmax is a given temperature that is set within a range equal to or higher than 2300°C; and at the fourth step, if the in-furnace superficial gas velocity u does not satisfy the above expression, the injection rate of the oxygen-enriched air is decreased so that the in-furnace superficial gas velocity u satisfies the above expression. a first step of adjusting a charging rate of the coke while monitoring a furnace-top temperature T top; a second step of adjusting an injection rate of the pulverized coal while monitoring an in-furnace superficial gas velocity u and the furnace-top temperature T top; a third step of adjusting an oxygen-enrichment ratio of the oxygen-enriched air while monitoring a combustion temperature T f at the tuyere and the furnace-top temperature T top; and a fourth step of determining whether an injection rate of the oxygen-enriched air needs to be adjusted, based on a value of the in-furnace superficial gas velocity u, when the charging rate of the partially reduced iron is increased, at the first step, the charging rate of the coke is decreased within a range where the furnace-top temperature T top satisfies the following expression: T top ≥ T topmin wherein in expression, T topmin is a given temperature that is set within a range equal to or lower than 120°C; at the second step, the injection rate of the pulverized coal is increased within ranges where the in-furnace superficial gas velocity u and the furnace-top temperature T top respectively satisfy the following expressions and: u ≤ u max T top ≤ T topmax wherein in expression, u max is a given velocity that is set within a range from 100 to 150 m/min, and in expression, T topmax is a given temperature that is set within a range equal to or higher than 180°C; at the third step, the oxygen-enrichment ratio is increased within a range where the furnace-top temperature T top and the combustion temperature T f respectively satisfy the above expression and the following expression: T f ≤ T fmax wherein in expression, T fmax is a given temperature that is set within a range equal to or higher than 2300°C; and at the fourth step, if the in-furnace superficial gas velocity u does not satisfy the above expression, the injection rate of the oxygen-enriched air is decreased so that the in-furnace superficial gas velocity u satisfies the above expression.