Abstarct: The present study investigates the effect of organizational pessimism on the happiness of the employees of Gandleh Opal Parsian Company with the mediating role of resilience. This research is considered as an applied research in terms of purpose and is structural equation modeling in terms of method. The statistical population of this study consisted of 425 employees of Opal Parsian Pellet Company and considering all employees using Cochran's formula, 202 people were randomly selected as the research sample. In the present study, due to the nature of the research subject, information was collected through the organizational pessimism questionnaire of Kalagan et al. (2009), Oxford Happiness (1990) and organizational resilience baxsed on McManus model (2015) and to analyze the data from equations. Structure was used and SPSS-22 and AMOS-22 software were used in all statistical analyzes of this study. The results showed that organizational pessimism with the mediating role of resilience has an effect on the happiness of the employees of Gandleh Opal Parsian Company. Also, organizational pessimism affects the happiness and resilience of the employees of Gandleh Opal Parsian Company.