To provide a method for advantageously operating a coke oven capable of arbitrarily mass-producing coal tar having desired characteristics according to the demands of consumers.

In at least a part of carbonization chambers of a coke oven, the amount of coal charged to the carbonization chambers is increased and decreased and the number of the carbonization chambers subjected to increase and decrease adjustment of charged coal is controlled. Consequently, the coke oven is operated so that tar QI of coal tar obtained from a coke oven gas is changed and a fixed amount of coal tar having a given tar QI is formed.