Purpose: The purpose of this study was to prove the influence of method biases of social desirability on the sequential process of basic psychological needs → motivation → flow and emotion, suggested in HMIEM. Methods: This study conducted a questionnaire survey with 307 high school athletes. Structural Equation Model was employed to look into the scale of common method biases induced by social desirability. Results: As a result, a, b, and c, each of which is factor loading prior to control of social desirability, were .76, .80, and -.31, as shown in figure 2. Each factor loading after control of social desirability (shown in table 2) fell to .43, .56, and -.18. With regard to the SMC of each latent variable prior to control, the SMC of motivation was 57.5%, that of flow 63.5%, and that of emotion 9.8%. However, after control, motivation's SMC remarkably fell to 18.5%, flow's to 31.2%, and emotion's to 3.2%. Conclusion: Therefore, social desirability, one of common method biases, influenced the research model.