Our main goal in this study was to resolve the difficulty of facilitating problem-solving-learning in schools, where all facilitators carry out the effective facilitation of Problem/Project Based Learning (PBL) that satisfies a certain quality. This paper discusses a "Project /Problem Based Learning Body of Knowledge (PBLBOK)" that was developed to enable facilitation suitable for learning scenarios. We refer to the project management method, classify causes from learners having fallen into difficult situations, and define the viewpoints, processes, and intermediate artifacts (deliverables) of PBL in the development of PBLBOK. We then describe how we organized the knowledge to facilitate PBL. PBLBOK provides viewpoints, processes, and deliverables of facilitation, and also provides viewpoints for the evaluation of PBL by referring to the project management framework. We found that teachers could efficiently and effectively facilitate and evaluate PBL by using PBLBOK.