The present invention relates to a method of producing a macrocyclic transition metal complex, comprises the steps of: preparing a diformyl compund by mixing trimethylindolenine and dimethylformamide, and phorphoryl chloride, under cool condition to form a resulting mixture and subsequently heating said resulting mixture followed by basification; reacting the diformyl with diamine in lower alcohol containing acid to produce a macrocyclic ligand; mixing a transition metal (II) salt with the macrocyclic ligand under heat with dioxane and triethylamine; and refluxing said mixture to produce the macrocyclic transition metal complex.