由於金融管制的鬆綁以及國際化的潮流所趨，國內銀行業面臨競爭日益激烈之金融環境。而我國銀行業近年來因獲利能力下降、盈餘衰退等問題，往往為了追求較高的利潤，放鬆放款條件，因而使放款品質惡化並增加其面臨風險之程度。為了探討放款品質以及風險對於銀行經營效率與規模經濟的影響，本研究利用Battese and Coelli (1995)之模型，以民國84至93年間50家銀行為研究樣本進行成本效率與規模經濟之分析，並在模型中納入逾放比率與資本適足率分別作為放款品質與經營風險之代理變數。實證結果顯示： 1.為金控底下之子銀行、資產規模愈大、分行家數愈多對於成本效率之提升有負面影響。 2.資本適足率愈高的銀行其成本效率愈高。 3.我國民營銀行之成本效率及規模經濟皆優於公營銀行。 4.按銀行規模大小比較，則規模大的銀行比規模小的銀行較不具成本效率，但前者之規模經濟大於後者。 Due to the deregulation of financial market and the trend of globalization, banks in Taiwan face a more and more challenging environment. Because of these external changes, Taiwan’s banking industry is experiencing declining profitability and earnings recession. Thus, in order to woo higher profits, banks often easily loose their lending requirements, which could deteriorate their loaning quality and increase the degree of operating risk. With this concern, this thesis applied the model of Battese& Coelli (1995) to investigate how loaning quality and operating risk will affect the scale of economy and cost efficiency of banks in Taiwan,. The data is an unbalanced panel data including 50 banks over the period from 1995 to 2004. In the model, the ratios of overdue loan and capital adequacy are used as proxy variables for loaning quality and operating risk. The received results are as follows： 1.A bank which belongs to financial holding companies, large bank asset and more branches make negative effects on banks’ cost efficiency. 2.The bank with higher capital adequacy ratio has higher cost efficiency. 3.Private-owned Banks, in general, have better scale of economy and cost efficiency than government-owned Banks. 4.Banks with larger assets have lower cost efficiency than those with smaller assets, but the former have better scale of economy than the latter.