本文旨在研究存在污染的混合寡占市場下，廠商具有企業社會責任的概念，對於廠商生產策略和利潤會有何影響，以及探討政府如何訂定最適污染稅。本文研究混合雙占市場中，當政府課徵的污染稅越高，民營廠商會減產、公營廠商會增產。我們發現當每一單位排放的邊際環境損害增加時，公營廠商將會減少產量，民營廠商則會視注重 CSR 程度而減產。當民營廠商越重視企業社會責任，政府制定的污染稅會越低。我們接著探討市場存在一家公營廠商和多家民營廠商時，發現當民營廠商家數增加會使得公營廠商和民營廠商減產。民營廠商數量增加，會使得課稅的起徵點越低，政府將課徵一個較高的污染稅，使得社會福利增加。;The purpose of this paper is we analyze the impact of the concept of corporate social responsibility (CSR) on firms in mixed oligopoly market with, and how the government imposes the pollution tax. We find the change of the firms’ production strategy and porfits when the government imposes the optimal environmenral tax. When the government imposes a higher environmenral tax, a private firm will reduce production and a public firm will increase production. Besides, we also find that when the marginal environmental damage per unit of emissions increases, a public firm will reduce production, and a private firm will reduce production according to how much the private firm cares about the environment . When private firms pay more attention to corporate social responsibility, the government will impose a lower environmenral tax. Eventually, we discuss the situation of a public firm and several private firms in the mixed oligopoly market. We find that when the number of private firms increase, the output of public firms and private firms decreased. The increase in the number of private firms will make the threshold of environmenral tax lower, and the government will impose a higher environmenral tax, which will increase social welfare.
