The background of this research is the inconsistency of the results of previous research about the factors that influence moral disengagement. This study aims to determine the role of critical thinking as a mediator of the influence of internal locus of control on student moral disengagement. The population in this study were 1560 students of the State Islamic University (UIN) Sunan Gunung Djati Bandung who lived in boarding schools around the campus with a total of 300 respondents taken randomly. Data collection uses internal locus of control (ILoC), critical thinking (CT), and moral disengagement (MD) scales. Based on structural test results it is known that internal locus of control has a positive and significant effect on critical thinking, internal locus of control has a negative and significant effect on moral disengagement, and critical thinking has a negative and significant effect on moral disengagement. The results of the model test with structural equation model (SEM) show that critical thinking plays a negative and significant role as a mediator between the influence of internal locus of control on moral disengagement.