In an environment of high uncertainty, risks in corporate management are changing daily. However, risks do not occur independently, but are often caused by a variety of events (risk factors), including other risks. We define this as causal relationships between risk factors. In addition, a single risk factor may have multiple consequences. For example, when a risk factor such as the Covid-19 epidemic occurred in one company, some departments increased sales due to increased IT investment, while others suffered losses as a result of reduced advertising due to worsening business conditions (risk factors of worsening business environment). Therefore, when actually understanding and assessing the risks faced by a company, it is necessary not only to understand the risk factors, but also to understand how they will ultimately affect business performances. In other words, it is important to stratify the risk factors. In this study, we propose a method to obtain the causal content of extracted risk sentences and to understand the risk factors using a hierarchical structure.