Emerging technologies driven by Network Function Virtualization (NFV) and Software Defined Network (SDN) should be implemented with high quality software. Lower service prices are necessary for carrier networks that provide conventional telephone services on an internet service network. However, the development and maintenance costs tend to remain high because the telephone services must be reliable and secure as they are valuable social infrastructure. Although the communication facilities that provided the backbone of communication infrastructure have become dramatically cheaper to run as hardware has been commoditized and virtualized, the software used in these facilities must guarantee sufficient quality and security. Thus the software development process requires various quality improvement measures, so the development cost remains high. To automate the software development process to solve this problem, we propose a method for automatically generating homogeneous test cases of the system testing phase that does not depend on the skills or know-how of engineers who interpret requirements specification documents written in natural language. We also implement a trial system for automatic test case generation to evaluate the effectiveness of the proposed method.