This study aims to examine the effect of competence, independence, experience, and audit time pressure on fraud detection by using the mediation of professional skepticism in the context of internal auditors for the public sector. The research data were obtained through a survey questionnaire on 173 auditors of the Inspectorate General of the Ministry of Education and Culture. The analysis technique in this study used Partial Least Square (PLS). The results showed that competence, independence and audit time pressure had no effect on the ability to detect fraud. Meanwhile, the auditor's experience and professional skepticism had a positive effect on fraud detection. The application of professional skepticism was proven as a mediating variable in the effect of competence, independence, experience and audit time pressure on fraud detection. Auditors’ competence, independence, and experience had a positive effect on professional skepticism and audit time pressure had a negative effect on professional skepticism. The results of this study provide an input that the importance of applying professional skepticism could improve fraud detection.