At present the management is interested in the services of internal auditing, which has been in practice in Thailand only for a few decades. This is due to the enlargement of the size of business, the changes in the structure of organization, the development in the technique of management, together with the increased complexity in the practice procedures. All these factors make the top management unable to recheck the performance of staff at every level under his control. In order to ensure that the management operates efficiently and that the operating result is in line with the objectives of business completely, it is essential for the management to provide an effective internal control system which is able to recheck and audit at all time as required by the nature of business. Internal auditing plays an important role in a sound internal control system. It is an important tool for sound management. The writer deems it necessary to study the principle of internal auditing and the practice procedure as is prevailed in Thailand. She considers in particular the independence of auditor in performing the work of auditing and the reliability of the end-result of the internal auditing work, which can be evaluated from and reflected in the liberty in reporting. The writer sincerely hopes that the findings in her thesis can be used in improving the efficiency of internal auditing system. Data used in this thesis were excerpted from foreign text books, together with the writer’s personal observation of the performance of internal auditing staffs and her inquiries from general auditors in various organizations in Thailand. From the result of research it can be summed up as follow: The internal auditing practice system in Thailand has reached the level of management auditing in a few large financial organizations. In general the internal auditors’ independence is limited to only the authority allocated by the management buy they have full liberty in reporting. The internal auditors’ influence to the organization depends largely upon the knowledge of the auditors themselves, the experience of the internal audit staff members and the management’s attitude towards the finding of the internal auditing department. The writer deems it necessary to standardize the internal auditing practice, especially for those practicing sub-standard internal auditing at present. Improving the level and efficiency of the internal auditing may be achieved by means of giving more direct and indirect training to the auditing staff, such as organizing in-service seminars in their own department, or co-operating with professional associations in auditing conferences, or letting the audit staff receiving direct internal audit knowledge from the institutions of higher learnings which offer internal audit course, or the combination of the above-mentioned measures. The ultimate important factor in securing the effectiveness of internal auditing practice depends very much on the sound [judgment] and the impartiality of the top management in formulating a sound personnel policy by putting the right staff on the right job according to the knowledge and the experience of each person.
