Recently, it has been gradually believed that enzymatic reactions generally involve several enzyme-substrate complexes in their pathways. For such the reactions, an approximation technique, for instance, steady-state approximation or Michaelis-Menten approximation, may not be simply applied to analyze the experimental data. In the present study, a three-step scheme of enzymatic reaction was subjected as a typical example of enzymatic reaction to the digital computer simulation to establish the practical experimental conditions which allow the proper application of approximation technique in handling the experimental data.