Corporate governance mechanisms is a way to effectively use the resources by shareholders who are offered their financial resources to managers. In fact, one of the main purposes of these mechanisms, on the one hand, is to gain investors’ trust, to clarify financial markets and to encourage investors to greater investments in capital markets. On the other hand, the professional and unprofessional investors’ perceptions of these principles, would definitely lead to better investors’ decision making and therefore to better output for companies. This study focuses more thoroughly on some of the effective factors on the relation between corporate governance and the investors’ perceptions by dividing the investors into two groups of professional and nonprofessional investors. The study statistical population includes professional and unprofessional investors active in the Iran capital market. Samples were selected based on stratified random sampling. 60 investors of Tehran Stock Exchange as the sample were selected using Stratified random sampling and the relationship between corporate governance mechanisms and investor’s decisions was evaluated using a questionnaire. To test the hypothesis of Kolmogorov-Smirnov test for normality of data, confirmatory factor analysis, independent T test, using SPSS software were performed. The result showed a significant difference in both groups perceptions of corporate governance mechanisms. The most significant differences were in terms of institutional investment, ownership structure and independence of the executive board. No significant difference was observed between the two groups in terms of information clarity.