本研究旨在探討內部稽核單位規模之影響因素，透過問卷調查方式向國內上市櫃公司的稽核主管蒐集相關資料，藉此瞭解內部稽核單位的運作情形與稽核主管對其單位規模未來變動的看法。本研究發現： 1.內部稽核之功能對稽核單位規模有正向顯著的影響，顯示我國上市櫃公司係依據其內部稽核功能之強弱，以決定其稽核單位的規模。 2.內部稽核功能的影響因素係以機構的內在管理因素為主，包括治理單位的重視與要求、公司之資訊透明度以及組織內其他部門的配合，而內部稽核的相關法令規範亦為影響稽核功能的因素之一。 3.上市櫃公司稽核單位的規模在近三年來大多為持平的狀態，而目前的員工人數，仍以1至2人的小規模單位為主。我國稽核單位普遍面臨人力不足的情況，主要原因為機構所設定的內部稽核功能超過稽核單位的人力，以及缺乏特定專長的人員。目前稽核單位多採取減少低風險項目的稽核、提昇稽核效率與加班等方式，以因應人力不足之限制。 4.非金融業稽核主管，其大多認為未來稽核單位規模將持平；而金融業稽核主管則有近半數認為其單位規模會逐步增加，顯示金融業對於內部稽核單位的擴充較具信心。 / This purpose of this paper is to investigate the factors that significantly influence the size of a firm’s internal audit department (IAD). This paper also reports the status of IAD operations and chief audit executives’ (CAEs) opinions regarding the possible change in size of their departments. A research questionnaire was sent to the CAEs of listed companies in Taiwan to collect data for empirical analysis. The main conclusions of this study are as follows. 1.Internal audit functions positively influence the size of IAD. Most organizations determine the size of their IADs in accordance with their expected functions of internal audit. 2.There are four factors affecting the functions of internal audit, namely, the board of directors’ emphasis on internal audit, corporate information transparency, other departments` cooperation and coordination with IAD, and the laws and regulations on internal audit. 3.The size of IAD remains stable for the past three years. The size of IAD is very small. For most IADs, there are only 1 to 2 auditors, and lots of IADs are experiencing shortage in manpower. The shortage is mostly due to the board’s expectation of IAD exceeds the current capability of IAD and its lack of specialty personnel. To overcome the constraint in manpower, most IADs decrease the audit of low-risk items, increase audit efficiency and/or work overtime. 4.Most CAEs believe that the size of their IADs will not change significantly in the near future. However, the CAEs in the banking industry generally believe that the size of their IADs will increase gradually.