We propose utilizing a fuzzy cognitive map(FCM) to integrate tacit knowledge and explicit knowledge both of which are crucial to the success of knowledge management. Recently, explicit knowledge is getting more available as CRM and data mining approaches become popular as the advent of using database and the Internet technology. However, for the knowledge management to be successful, tacit knowledge should be seamlessly integrated with explicit knowledge seamlessly. The problem hindering such effort is how to find a vehicle facilitating transformation of explicit knowledge into tacit knowledge, and vice versa. FCM has been important method for representing tacit knowledge as a form of explict knowledge. In this respect, we suggest the detailed process about how to integrate explicit knowledge and tacit knowledge by using FCM. We gathered extensive set of data from the credit card company, and applied our proposed method. Results showed that our approach is robust and promising for the field of integrating two different kinds of knowledge.