中文摘要：

本文以我国2007-2011年受到监管机构处罚的违规公司为研究样本，研究了法律环境、媒体监督与代理成本之间的动态关系。研究发现：在这些违规样本公司中，上市公司所处法律环境越好，公司的代理成本越低；媒体的负面监督越多，公司的代理成本越低；在不同的法律环境下，媒体监督对代理成本的影响不同。进一步的研究还发现，无论是国有上市公司还是非国有上市公司，法律环境的提高都可以降低公司的代理成本，而媒体监督对代理成本的影响在不同股权性质的公司却表现出了差异。综合本文的研究结果，作者认为可以完善法律环境、加强媒体监督来加强对中小投资者的利益保护。

英文摘要：

This paper studies the dynamic relationship among legal environment, media supervision and agency cost based on sample companies subject to regulatory penalties for violations in 2007 to 2011. The results show that listed companies in better legal environment have lower agency cost, the more media supervision, the lower agency cost of the company, media supervision have a different influence on agency cost in different legal environment. Further studies show that no matter in state- owned companies or in non-state-owned companies, the improvement of legal environment can reduce the agency cost, but media supervision have a different influence on agency cost in different ultimate controlling shareholder company. Finally, we think we can improve legal environment and strengthen media supervision to strengthen investors＇ protection.