This invention is to automatically carry out the retracement of the knowledge. Therefore, this method is executed by a computer having a retracement data storage storing a target type of a past project, data concerning a scale of the past project, a specific phase of the past project, data concerning a problem in the specific phase of the past project, and data concerning an action against a problem in the specific phase of the past project. Then, this method comprises: obtaining project data including a target type of a project, data concerning a scale of the project, and a pertinent phase of the project; calculating an overall similarity for the retracement data of each past project, which is stored in the retracement data storage, by using a first similarity against the target type of the project, a second similarity against the data concerning the scale of the project, and a third similarity against the phase of the project; reading out, based on the overall similarity, from the retracement data storage, the data concerning the problem in the specific phase of the past project or the like.