This study analyzed the effect of high managerial ability and financial flexibility on tax avoidance.The results of the study are as follows: First, a significant negative (－) relationship was shown in the verification of relevance between managerial ability and tax avoidance, showing the result that the higher the managerial ability is, the more likely it is to avoid tax avoidance behavior that may be negative for corporate value according to the agent theory perspective. Second, a significant negative (－) relationship was shown in the verification of relevance between managerial ability and tax avoidance and companies with higher financial flexibility were found to avoid active tax avoidance behavior rather than choosing tax avoidance which is the purpose of the tax reduction effect on the operating profit caused by active investment activity because it may act as a negative factor in corporate value. It also means that companies with high financial flexibility have higher levels of debt financing and therefore, the tax savings effect on interest costs will lower the level of tax avoidance in the substitutional relationship.