在代理架構下，經理人可藉由從事租稅規避、社會責任活動進行尋租，因此可能產生經理人與股東間的代理問題。增加經理人權益誘因可以產生利益一致效果，降低代理成本。然而當經理人持有重大比例股權，可能引發控制股東經理人進行利益侵佔，反而形成控制股東侵佔少數股東利益的代理問題。由於租稅規避、社會責任活動可能衍生代理成本，而代理成本與經理人股權有關，因此本研究認為經理人持股高低會影響企業社會責任與租稅規避之關係。本研究以台灣上市櫃公司為樣本，研究期間為2010年至2016年，以經理人持股比例作為調節變項，檢測企業社會責任與租稅規避之關係。實證發現如下：（1）社會責任表現愈佳之企業其有效稅率愈高，顯示具有社會責任之企業較不會進行租稅規避，支持利害關係人假說觀點；（2）經理人持股比例愈高，企業的有效稅率愈高、財稅差異愈小，表示經理人持股愈高之企業愈不會進行租稅規避；（3）有限證據顯示經理人持股對企業社會責任與租稅規避之負向關係有調節效果。本研究發現當經理人擁有高度股權時，控制股東經理人可能藉由企業社會責任活動掩飾租稅規避的利益侵佔行為，因而在經理人擁有高度股權情況下，無法觀察到經理股權對企業社會責任與租稅規避之關係有顯著調節效果。 From the traditional agency theory perspective, managers may hide rent extraction through tax aggressiveness and social responsibility activities. Existing theories propose that greater managerial ownership generates greater alignment of the interests of managers and shareholders and thus reduces the agency costs. On the other hand, increasing managerial ownership may entrench managers, causing agency conflicts between the controlling owner who is also the manager and minority shareholders. Using a sample of Taiwanese listed companies from 2010 to 2016, this study investigates whether socially responsible firms are less or more tax aggressive, and whether this relationship will be impacted by managerial ownership. This study finds that firms with high CSR have higher effective tax rates, supporting the stakeholder theory. In addition, this study finds that firms with higher managerial ownership are less tax aggressive, consistent with the alignment effect argument. This study finds only limited evidence that managerial ownership has a moderating effect on the negative relation between CSR and tax aggressiveness. However, when managers own a significant equity ownership, this study finds no evidence that managerial ownership moderates the negative relationship between CSR and tax aggressiveness. This suggests that owner-managers might increase CSR activities to mask their rent extraction through tax aggressive activities.