本文擴展過去僅限於上市 (櫃) 審計市場之市場結構研究，探討因證券交易法及財政部行政命令須聘任會計師事務所查核簽證之我國三大審計市場的供需特質及其市場結構。根據財團法人金融聯合徵信中心之資料庫，本文衡量民國81至87年度台灣上市 (櫃)、公開發行、以及在金融機構總授信歸戶金額達三千萬以上之融資審計市場之市場集中度與赫芬達指數，除了觀察年度問台灣三大審計市場結構變化外，並與國外主要審計市場結構之實證結果進行比較分析，期能對台灣整體審計市場之結構提供重要之實證證據。研究結果發現，國內三大審計市場之結構與國外審計市場相近，上市 (櫃) 審計市場日益傾向於緊密寡佔、公開發行審計市場傾向於寬鬆寡佔、而融資審計市場則傾向於獨佔性競爭及完全競爭市場之市場結構型態，且與美、英、紐、德、荷等國之實證結果相近；市場中公司規模則為影響審計市場結構之重要變數。

This paper investigates the structures of three audit market segments in Taiwan based on the perspectives of theory of industrial economics. We divide the Taiwan audit market into Listed (OTC), Public-traded, and Loan-purpose audit market segments based on the different demand and supply characteristics for audit service, in addition to the different audit service related regulations among these three segments. This paper calculates the concentration ratio and the Hirschman-Herfindahl Index for all the three audit market segments from the years of 1992 to 1998, respectively. Based on the empirical results, we suggest the List (OTC) audit market segment tends to be the tight oligopoly, and the Public-traded audit market segment tends to be the loose oligopoly market structure. For the Loan-purpose audit market segment and the whole Taiwan audit market, we suggest that their market structures are between the monopolistic competition and pure competition category. Our empirical measurements of Taiwan audit markets' structures are similar to the market structures of the United States, United Kinden, New Zealand, Germany and Netherlands. The size of the auditee in the audit market segment is the major influence factor of the audit market structure.