In the railway construction project, there are potential risks that cause Contract Change Orders and has an impact on project cost performance. Risk factors can be seen from three aspects that consist of technical, legal, and environmental aspects. Therefore, the purpose of this study is to analyze the factors causing CCO that have an impact on costs, and determine the steps for managing CCO risk. This study uses a questionnaire to the experts which has experience on railway projects. From the research results, 29 risk variables that affect CCO are grouped into technical, legal and environmental aspects. The factors of design changes, changes in the scope of work and acceleration of the implementation schedule are one of the dominant factors causing CCO in this study. Furthermore, the identified risk factors can be used for the next step, which is to respond to the risk as a risk control strategy. This strategy is expected to improve the cost performance of railway projects.