中文摘要：

本文从双重代理成本视角实证检验媒体作为一种外部监督机制能否帮助上市公司缓解代理问题。考虑到媒体报道与公司代理问题之间的相互影响．本文采用联立方程模型对内生性问题进行控制。本文基于中国A股上市公司2006～2009年数据的实证分析结果表明，上市公司的双重代理成本——股东与管理者间的第一类代理成本和大股东与中小股东间的第二类代理成本越高，受到的媒体关注和报道就越多，而高水平的媒体报道能够有效降低公司的双重代理成本，且媒体报道的上述治理作用在第一类代理问题中表现得更强。进一步，本文还分析了媒体与市场化环境两种目前学术界最为关注的外部监督机制间的交互影响。发现这两种机制的治理作用存在显著的替代效应。

英文摘要：

From multiple agency cost perspectives, this paper empirically examines whether media coverage can help alleviate agency problems. Given the existence of endogenous problem between media coverage and agency costs, this paper uses the simultaneous equations model to control the problem. Using the data of Chinese A - share listed companies from 2006 to 2009, it is found that the more serious a company＇s dual agency costs between shareholders and managers （Agency Costs I） and between large shareholders and minority shareholders （ Agency Costs II） are, the higher media coverage it gets. In turn, high levels of media coverage can effectively reduce the company＇s dual agency costs. These effects of media coverage are found to be stronger in Agency Problem Ⅰ than in Agency Problem Ⅱ. Further, this paper analyzes the interaction effect between media and marketization environment, and finds that these two external governance mechanisms have a significant substitution effect between each other. Key words： Media coverage, Corporate governance, Agency costs Ⅰ, Agency costs Ⅱ, Marketization environment