Critical Analysis on Najm ad-Dîn at-Tûfi’s concept of mashlahah. This study finds that at-Tûfi’s conceptof mashlahah has some weaknesses epistemologically and ideologically. First weakness is on its inconsistentuse of reason as a primary epistemology for the concept of mashlahah. On the one hand, at-Tûfi stated thatmashlahah is the most powerful argument (aqwa adillah al-syar’i). He has argued that if there is a contradictionbetween the text and mashlahah, then mashlahah must be given preference (izâ ta’âradat al-mashlahah wa annasfaquddimat al-mashlahah). Similarly, in the methodology, he lacked exploration on the concept of mashlahahwith theories and clear definitions. For example, he argues that mashlahah is the most powerful argument inmu’amalah, while the worship (muqaddarat) is the prerogative of God. However, he did not clearly define whatlegal actions are included in mua’malah and what actions are included in worship (muqaddarat). At-Tûfi alsofound “difficulty” in deciding between two things with the same mashlahah value theoretically, so he proposeddrawing lots (qur’ah). Second, the ideological weakness is visible from his mashlahah concept which is actuallyrational, yet it is stuck in the power of texts.