It has been well recognized that the reaction rates in equilibrium steps such as enzymesubstrate complex formation or transformation of the complex in the enzymatic reaction can only be measured by special techniques such as temperature-jump method, because the reaction velocity of equilibrium step not accompanying the molecular change is generally large beyond the limit of adoption of usual kinetic methods. The authors reported previously that the enzyme-substrate complex formation in the system of the substrate and the enzyme-inhibitor complex had quite smaller reaction rate than expected one. When the substrate was added to the solution of enzyme-inhibitor complex which was previously formed, it was found that the exchange of inhibitor with the substrate took about 90 min for the completion of a new equilibrium state. This fact leads us to suggest that the rate constant of the step of the enzyme-substrate complex formation would be measured by usual kinetic method, if the experiment is designed so as to involve the exchange of inhibitor by the substrate in the reaction system. Before measuring the rate constant of the enzyme-substrate complex formation based upon the above principle, it will be absolutely necessary to analyze the process of the enzyme-inhibitor complex formation to obtain the kinetic parameters of the system. The present article reports the results of kinetic analysis of the complex formation between lysozyme and the cationic detergent dimethylbenzylmyristylammonium chloride and some discussions on relevant subjects.