本文主要探究貪污議題對銀行海外投資的影響。全球化因素提高了銀行在海外投資時遇到貪污問題的可能性，也引起我們對此議題的關注。貪污究竟是妨礙投資活動的砂子或是加速的潤滑劑？一直是理論文獻的爭論焦點，但貪污在銀行跨國投資裡所扮演的角色則未有實證文獻探究。我們利用45個國家銀行在46個國家金融中心城市所設立的分行資料進行此議題的驗證，發現貪污會對海外投資產生負向影響，亦即貪污如同砂子，會阻礙跨國銀行分行投資活動的運行。我們亦進一步檢視兩國貪污環境差異的影響是否為負向，如果是負向，其負向影響是否會隨來源國貪污程度的增加而減少，也就是存在不對稱性，兩者皆得到證實。此結果顯示貪污環境差異性會增加跨國投資的進入成本，因而銀行較傾向在貪污程度相似的國家設立分行。不對稱的負向影響則意味著來自越貪污國家的銀行對於貪污環境差異性有相對較佳的適應能力，因此，我們建議銀行應培養高貪污環境因應能力以利於海外投資的進行。

This paper mainly investigates the impact of corruption on banks' overseas investment. The pattern of globalization has raised the likelihood that multinational banks will encounter corruption, which draws our concern about the above issue. Is corruption seen as sand or grease in the wheels of investment? The two views have been presented as competing arguments by theoretical studies, but no empirical study explores the playing role of corruption in banks' overseas investment. We use data on the number of foreign branches set up by banks of 45 countries in host financial center cities located in 46 countries to examine the impact of corruption on overseas investment and find the negative impact. Corruption is the sand that impedes multinational banks' cross-border investment and thus decreases foreign branch establishing. We also find the negative impact of corruption difference between two countries and its asymmetric effect. The first one indicates that corruption difference would increase the entry cost to foreign banks and result in negative investment decisions. The second one means that negative impact of corruption difference diminishes with the level of source-country corruption. It shows that bank from higher corruption country has better capacity to handle this difference. We suggest that multinational banks should improve the managing bribery skills to benefit their overseas investment.