After Section 404 of the Sarbanes-Oxley Act was released, developing an effective computer auditing system became critical for management and auditors. In this study, the researchers used Gowin's Vee, raised as a research strategy by Novak and Gorwin (1984). On the theoretical side, the researchers arranged documents and employed an expert questionnaire to identify 8 operational procedure elements and 34 critical factors for the purchasing and expenditure cycle. The application side was built upon the model. The researchers then developed the computer auditing system based on the developments of this study. To test the suitability of the system, the researchers conducted a case study whose results showed that this system can provide the company owners and their accountants with a simple, continuous, timely, and analytical method which may help them detect promptly any irregular internal control issues, thus identifying measures to improve the condition.