The process industry has caused many serious accidents since 2000. The causes are not only on the spot but are related to the management problems of engineering. For example, the correspondence which modifies the set-point of a control system is a part of the entire engineering activity. It is a very tiny change but it belongs to Management of Change because it may cause a serious accident. The conventional solution is derived from a local viewpoint but is not taken from a global viewpoint. This basic concept is summarized by 'Introduction to Information Integration' (Naka et al., 2006). This paper discusses the necessity of an engineering activity model as well as a technical information infrastructure that supports decision-making from multi-dimensional viewpoints. The model to is applied here to planning of a biomass network system, which is a kind of complicated socio-technical system.