Internal control plays a pivotal role in enhancing security operations and quality control in an organization. From the perspective of management, internal auditors work for ensuring effective operations and improving performance for all the management systems within the organization. They bear great responsibility and play a key role. This study aimed to explore the internal audit staff demographic variables of personality traits differences. This research selected samples of the internal auditors from domestic companies, i.e. members of the Institute of Internal Auditors, in Taipei, Hsinchu, Taichung, and Kaohsiung. A total of 567 questionnaires are issued and the number of valid questionnaires is 272.