In accordance with the increase in importance of software within railway signaling system, risk costs due to the software error are increasing too. Accordingly, software validation in various aspects is required, and the needs for supporting tool which can automate it are raised. In Korea, the black-box testing tool of railway signaling system taking into consideration of the convenience of use which was developed to solve demerits of existing commercial tools was proposed and developed recently. This tool is an approach which generates test data on the basis of the international standard test language, TTCN-3(Testing and Test Control Notation-3), and utilizes interfaces for actual use, and its convenience of use was enhanced in comparison with existing tools, and more effective test is possible with it. This paper describes the system-level black-box testing process on the on-board control system which is one of the railway signaling systems and its result by utilizing this tool. In addition, it considers effects of study and direction of development in the future on the basis of its result.