Abstract: The goal of this research was an investigation and explanation of local model of internal effective factors on stock price index in Tehran Stock Exchange (ISE) with fuzzy approach. Based on, it was reviewed literature of stock price index in special. The statistical population and sample were 500 and 150 elements, data collection instruments were documents, interviews and specially questionnaire with reliability of 0.85 as nonexprimental survey research, to explanation of local model with emphasize on fuzzy and using SPSS v.15 and FuzzyTech v.5.61 software. The results showed in the entire internal factors, managerial, marketing and structural variables have the most effect on stock price index. Finally, it is presented concluding, discussion, implications for managers and directions for further research.