A computer-understandable knowledge base for accumulating computer-understandable task knowledge and a know-how knowledge base for accumulating know-how knowledge understandable for a human being are provided. In accordance with, for example, a result of the process for solving a problem which has been performed by the computer-understandable knowledge base 1, know-how knowledge relating to the problem solution is automatically retrieved and presented. Since know-how knowledge relating to the problem solution is automatically retrieved and presented in accordance with the state of the problem solving process which has been performed by the computer-understandable knowledge base, a user is able to efficiently make a reference to required know-how knowledge without a complicated process for conditions for retrieving the know-how knowledge. Even if a problem cannot be solved by the computer-understandable knowledge base, the know-how knowledge is used to guide the problem solution.