The tone is characterized by the ratio of positive and negative words contained in the annual reports of the board of directors, which can be based on two Incremental Information  and opportunistic views. An Incremental Information view reduces information asymmetry, while an opportunistic perspective in the form of perceptual management is used to manipulate and distort user perceptions. Corporate governance acts as a mechanism for reducing the opportunism of managers.The purpose of this research is to examine the impact of corporate governance on Tone of financial reporting. In this research, to assess the corporate governance of the Topsis system, which consists of six criteria for the independence of the board of directors, management ownership, duality of the CEOchr('39')s duties, quality Audit, institutional ownership, and ownership concentration. The research sample which has been chosen by systematic elimination method is consists of 119 companies accepted in Tehran Stock Exchange for years 2010 to 2016. To test the research hypotheses, multivariate regression with panel data has been used. The results show that the stronger corporate governance is, it increases pessimistic tone. In other words the stronger corporate governance will prevent opportunistic managers who use tone in perception management