There are many opportunities for our communication and consideration to draw diagrams and pictures. We have been studying a human-machine interface which accepts diagrams and understands their meanings in application domains, and proposed a useful and flexible system. The system has a rule-based inference mechanism and recognizes the domain where the diagram should be understood. In this paper, we construct an interface system to communicate in natural language (Japanese). In addition to the inference mechanism, the new system consists of three subsystems : a decomposition mechanism of input sentences, a conversion mechanism of sentences into command lines and a drawing system. These subsystems presents an integrated interface which makes communication with diagrams more natural and practical.