The diploma work is focused on the internal audit issue. The goal of the work is on a basic of theoretical knowledge and practical experience to explain and describe the internal audit and the internal auditor job. The work is divided into the theoretical and practical part. The theoretical one is focused on the internal audit history, internal auditor character and profession, internal audit quality assessment and compare internal audit with the external audit. The practical one is focused on the internal audit unit in the business company and at first describes the internal audit regulatory frame and after that is already focused on the internal auditor job from audit planning, over the audit performance and audit report, to the monitorin...