Actually social capital is not a new idea, but the circumstances that have resulted in a novel approach to its concept, significance and benefits are new. Social capital, as a relationship that people establish among one another, became a significant concept and drew the attention of social scientists in 1990's. The existence of suitable background of social debates on organization and management has swiftly promoted the studies on social capital and its application on organizational research. Organizational social capita is defined as a source originated in social relation within an organization. This has been specified through collective goal and shared trust among the members' levels. Social capital is a collective feature of a byproduct of the organizations' activities, which complements collective action, and is a management phenomenon, possessing these features: trust, norms, values, shared behaviors, communication, collaboration, mutual commitment and cognition and networks. These are the reasons why organizations consider social capital seriously: 1. The significance of organization on the basis of Knowledge; 2. Economic is considered to be networked. Owing to its nature, social capital can have its own strengths and flaws for the organization, and social capital development necessitates the estimation of costs and relative profits derived from it. This calls for the attention and interest of managers of the field. The aim of this article is to introduce social capital concept and to justify the reason why organizations take it so seriously.