One of the most important issues in the field of organizational behavior studies is the identification of positive psychological resources and capacities, which considerably affect individuals’ job performance. Therefore, the present research aims to study and identify the effects of attachment on psychological capital. With regard to the purpose, this research is applied and in regard to data collection method, it is descriptive/analytic and of correlational type. The analysis is carried out based on Structural Equation Modeling (SEM). The study was done at Tehran Children’s Hospital, in which a sample of 176 personnel filled out the questionnaire. In this research, the validity of attachment and psychological capital measurement models was evaluated by Confirmatory Factor Analysis. Also, the results of the structural model suggested the significant effect of attachment on the dimensions of psychological capital. It is noteworthy that between the two dimensions of attachment, i.e. avoidance and anxiety, avoidance is more explanatory. Finally, it is notable that attachment theory is one of the most important theories in OB/HR; this has critical consequences for variables like psychological capital.