Decision-Making process is one of the important factor in organization and the managers who act optimization can guide successful organization. In this research the relationship Biorhythmic cycles has been investigated that influence on decision making of investing managers on investment funds in Iran’s capital market. The biorhythm components include "physical" cycle, "Emotional" Cycle, "Intellectual" Cycle and "six" sense and the components of error financial decision such as "compare", "commitment", "information bias", "cognation bias", "confidence bias" and "rare effect". The research method is descriptive and from the aim standpoint it is applicable. The sample estimate by Cochran formula and the questionnaire distributed between them randomly. Reliability and validity controlled, and the reliability based on Cronbach's alpha was 0.88. The hypothesis has been tested by spearman correlation and based on it, there is significant relationship between " Intellectual Cycle", "physical cycle", "six sense" and error financial decision. Finally to answer the research question, the structural equation to show the relationship between error financial decision and biorhythm cycles that showed biorhythm cycle effect on error financial decision is 0.33. For ranking the component of error financial decision the Friedman test was used. Finally, we offer some suggestion for researchers, organization, Investment Funds and Managers of Investment Funds.
