Resumo. ABSTRACT The aim of the present study was to path analysis of the hypothesized model of the irrational beliefs on the constructs of the planned behavior model, in particular the physical activity intention, and also the prediction of the physical activity intention based on the constructs of irrational beliefs. 320 male and female students of Semnan Province were randomly selected and completed Planned Behavior and Irrational Beliefs (Ahwaz) questionnaires. A path analysis model was used to analyse the relationships between variables and calculate the direct and indirect structural effects. Also, multiple regression analysis was used to predict theoretical constructs of planned behavior using irrational beliefs dimensions. The results indicated that the hypothesized model is not in accordance with the data of this study and direct effect of irrational beliefs on subjective norms is not meaningful. By eliminating the effect of irrational beliefs on subjective norms and adding the effect of subjective norms on perceived behavioral control, a new model was obtained that was fitted with the data. Also, the results show that two variables of Demand for approval and problem avoidance were significant predictors of physical activity intention. The results of this study showed that irrational beliefs, both directly and indirectly (through attitudes and perceived behavioral control), have an effect on the physical activity intention. Therefore, it is important to reduce the irrational beliefs in order to develop the intentions of physical activity and the physical activity itself.