This paper proposes a conceptual model for analysis method of extracting unexpected obstacles in order to improve the quality of embedded systems. Although embedded software has become increasingly large in scale and complexity, companies are requiring the software to be developed with in shorter periods of time. This trend in the industry has resulted in the oversight of unexpected obstacles and consequently has affected the quality of embedded software. In order to prevent the oversight of unexpected obstacles, we have already proposed two methods for requirements analysis: the Embedded Systems Improving Method (ESIM) using an Analysis Matrix, and a method that uses an Information Flow Diagram (IFD). However, these analysis methods have been developed separately. This paper proposes the conceptual model including both methods, and clarifies abstraction mechanisms of expert engineers for extracting unexpected obstacles of embedded systems. It also describes a case study and discussion of the domain model.