本文以轉換對數隨機邊界成本函數對台灣合夥型會計師事務所之成本效率進行估計，並探討會計師事務所特性對成本無效率之影響為何。經採台灣財政部發行2001年及2002年之會計師事務所資料加以分析後，主要發現有下列數端。首先，樣本期間內台灣合夥型會計師事務所之成本效率平均數為0.807，隱含約有19.3%成本減少之改良空間。其次，無論是有對公開發行公司進行財務簽證之高專業事務所或大型的事務所，其成本效率均較低專業及小型的事務所為差，連帶地利潤率亦較差，此一實證結果或可做為會計師事務所管理當局之決策參考。最後，會計師事務所規模對成本無效率具有顯著正向關係，顯示大型事務所無法透過學習曲線來降低成本；持續專業訓練對成本無效率具有顯著負向關係，意味著事務所投入專業訓練愈多，專業人員之素質因而提升，可同時促進查核效率，使得工作時數縮短且查核成本降低，故無效率成本降低。而分事務所太多則造成對無效率成本的正面影響，亦是值得管理當局注意的重要資訊。 This paper estimates the cost efficiency for the partnership accounting firms in Taiwan by using the conversion logarithms of stochastic frontier cost function, and investigate what firm-specific factors influence cost inefficiency. After using and analyzing the accounting firms’ data that the Ministry of Finance, Taiwan, published in year 2001 and 2002, the main findings are as follow. First of all, the cost efficiency for the partnership accounting firms in Taiwan in the sample period is 0.807, which implies there is about 19.3% space of improvement to reduce cost. Moreover, no matter is the high professional accounting firms that provide financial attestation service to stock-go-public company or big size ones, their cost efficiency are lower than the low professional and small size ones, and the profitability is also worse. This empirical result can be used as a reference of making decision for the management of accounting firms. Finally, there is a positive relation between firms’ size and cost inefficiency, and it implies big accounting firms can''t reduce cost through the learning curve. Also, there is a significant negative relation between the professional training and the cost inefficiency; it means the more professional training that firms devote, the more quality and the audit efficiency that professional employees improve, therefore working hours and audit costs reduce. It is an important information that the accounting firms with too many branches have a positive influence for the cost inefficiency is also an attention for the management.