隨著銀行業管制的解除，新銀行的開放設立使會計師在銀行業的審計市場擴大許多。銀行業受法令規範的程度較高，業務種類繁雜且多半與現金有關，其查核程序和其他產業不盡相同。Eichensecher & Danos (1981)的研究指出當客戶產業受規範的程度愈高或在資本市場的活躍程度愈高，會計師在查核這類客戶時規模經濟愈大，審計市場的集中度也就愈高。Hogan & Jeter (1999)則發現審計市場的產業集中程度，會隨著時間的經過而增加；而會計師事務所審計集中程度，在客戶為受管制的產業、較具集中度的產業與快速成長的產業中較高；但在具有高訴訟風險的產業中較低。 本研究欲探討會計師在查核銀行業時，審計市場集中度是否因產業的特殊性而有所不同。以民國八十一年至八十八年之上市公司為研究對象，並進行迴歸分析。依據本研究之結果，可獲得以下的結論： 一、客戶所處產業受管制程度與會計師事務所審計市場集中度不呈顯著關係。 二、時間因素與會計師事務所審計市場集中度呈正相關。 三、在受管制之銀行業中，管制與時間因素之交互作用與會計師事務所審計市場集中度呈正相關。 / With deregulation in the banking industry, newly established commercial banks enlarged the CPA’s audit market. The banking industry is highly regulated by laws and has multiple operating activities related with cash. Therefore, the audit processes are different from other industries. Based on the research of Eichensecher & Danos in 1981, the CPA-firm concentration was a positive function of the degree of client-industry regulation and capital market activity. Hogan & Jeter in 1999 concluded that levels of concentration had increased over time. Auditor concentration levels are higher in regulated industries, in more concentrated industries and in industries experiencing rapid growth, but lower in industries with a high risk of litigation. The purpose of this study is to answer the question whether auditor concentration levels in the banking industry are different from those in other industries. By using regression, the firms listed in Taiwan Stock Exchange for the period from 1992 to 1999 are investigated. Based on this research, the following conclusions are reached: 1.The relationship between the level of regulation on client's industry and auditor concentration is not significant. 　2.The relationship between time factor and auditor concentration is positive. 　3.The interaction of regulation and time factors is positively related with auditor concentration.