This study explores the measurement of the effectiveness of internal audits from the perception of internal auditors to prevent fraud. It examines the antecedents that affect the effectiveness of internal audits to prevent fraud. This study uses a mixed-method exploratory sequential design approach called instrument development design. This research's unit of analysis is the local government's internal auditor, namely the Financial and Development Supervisory Agency (BPKP), representing the Province of North Sulawesi, and the Inspectorate of the entire Province of North Sulawesi. The data collected were 165 questionnaires, and the analysis technique used PLS. The results of this study, audit effectiveness for fraud prevention is affected by audit quality. Then, the higher the independence of the internal auditor's functions in audit assignment, the better the audit quality, which will increase the effectiveness of internal audit in preventing fraud.