A process for producing a charge control agent comprising an azo-based iron complex salt compound as an effective component, comprising steps of: (A) obtaining a monoazo compound represented by the following general formula through diazotization coupling; wherein, p is an integer of 0 to 4 indicative of the number of R 1 group, q and s are each an integer of 0 to 5 indicative of the numbers of R 2 group and R 3 group, respectively, and R 1 to R 3 are each a deuterium atom, halogen atom, nitro group, hydroxyl group, alkyl group, alkenyl group, alkyloxy group, sulfonalkyl group, alkylsulfonate group, sulfonate group, carboxyl group, carboxyester group, sulfonamide group, acetylamino group, benzoylamino group, aromatic hydrocarbon group or aromatic heterocyclic group, with the proviso that when a plurality of R 1 groups, R 2 groups or R 3 groups are existent, said R 1 groups, said R 2 groups or said R 3 groups may be different from one another; and (B) ironizing the monoazo compound in a solvent at a reaction temperature of 60±5°C while pH is kept at 7.0 to 7.5 to produce an azo-based iron complex salt compound represented by the following general formula ; wherein, p, q, s and R 1 to R 3 are as defined in the above general formula , and A + is a cation, wherein in step (B), ferric chloride is added as an ironizing agent and the reaction time is 7 to 8 hours, and wherein the reaction liquid obtained in step (B) containing the azo-based iron complex salt obtained in step (B) is alkali treated by adding dropwise an aqueous solution of an alkali metal hydroxide. (A) obtaining a monoazo compound represented by the following general formula through diazotization coupling; wherein, p is an integer of 0 to 4 indicative of the number of R 1 group, q and s are each an integer of 0 to 5 indicative of the numbers of R 2 group and R 3 group, respectively, and R 1 to R 3 are each a deuterium atom, halogen atom, nitro group, hydroxyl group, alkyl group, alkenyl group, alkyloxy group, sulfonalkyl group, alkylsulfonate group, sulfonate group, carboxyl group, carboxyester group, sulfonamide group, acetylamino group, benzoylamino group, aromatic hydrocarbon group or aromatic heterocyclic group, with the proviso that when a plurality of R 1 groups, R 2 groups or R 3 groups are existent, said R 1 groups, said R 2 groups or said R 3 groups may be different from one another; and p is an integer of 0 to 4 indicative of the number of R 1 group, q and s are each an integer of 0 to 5 indicative of the numbers of R 2 group and R 3 group, respectively, and R 1 to R 3 are each a deuterium atom, halogen atom, nitro group, hydroxyl group, alkyl group, alkenyl group, alkyloxy group, sulfonalkyl group, alkylsulfonate group, sulfonate group, carboxyl group, carboxyester group, sulfonamide group, acetylamino group, benzoylamino group, aromatic hydrocarbon group or aromatic heterocyclic group, with the proviso that when a plurality of R 1 groups, R 2 groups or R 3 groups are existent, said R 1 groups, said R 2 groups or said R 3 groups may be different from one another; and (B) ironizing the monoazo compound in a solvent at a reaction temperature of 60±5°C while pH is kept at 7.0 to 7.5 to produce an azo-based iron complex salt compound represented by the following general formula ; wherein, p, q, s and R 1 to R 3 are as defined in the above general formula , and A + is a cation, wherein in step (B), ferric chloride is added as an ironizing agent and the reaction time is 7 to 8 hours, and wherein the reaction liquid obtained in step (B) containing the azo-based iron complex salt obtained in step (B) is alkali treated by adding dropwise an aqueous solution of an alkali metal hydroxide. <EOS>