Today, there are some dealings in many organizations to study that they are usually unwritten, but they impacts on employees' motivation and performance. The commitment of employees and organizations to their duties is a form of psychological contract. It is one of the categories that should be monitored and measured continuously. In recent years, we have seen rapid and explicit changes, in globalization, competition, deregulation, technology achievements, social, political and economic events. The hiring process is constantly changing and transforming. To put this in perspective, hiring employees have had significantly changed. Therefore, aspects of psychological contract have an essential role in leadership, managers and employees. We should pay more attention to this conference because the management science can familiarize organization with this types of subject. This study tries to investigate the mediating role of the psychological contract violation and the trust in the association between the psychological contract breach and the affective commitment. In this study, Data was analyzed with Structural Equation Modeling (SEM) and Analysis of Moment Structures (Amos), and the method of correlation-descriptive was used. Results indicated that there is a meaningful relation between the psychological contract breach, the trust and the psychological contract violation. Indeed, if the employees' way of thinking about their contract were different with their real contract, it would affect their feeling of trust in their organization. Thus, this trust may causes psychological contract violation. What's more, there is a meaningful relation between the trust, the psychological contract violation and the effective commitment. It means that change in the organizational trust can impact the psychological contract violation and the affective commitment. As a result, the relationship between the psychological contract violation and the affective commitment was approved.