<p>ESS (Endoscopic Sinus Surgery) requires advanced skills. Therefore, supporting surgeons in improving surgical skills is important. Hence, process analysis in production engineering need to be applied to complicated surgery such as ESS. In the previous research, ESS skill evaluation system using process analysis method was developed which enables detailed evaluation of surgeon skills per surgical process. However, the system requires declaration of surgeons and manual record of surgical process, so they have problem of interruption of surgery and manpower. Therefore, estimating the ESS process automatically is necessary for the ESS skill evaluation system. In this study, we propose the method of ESS process estimation by SVM (Support Vector Machine) based on CT data of patient and surgical tool trajectory data. This methods are evaluated in accuracy of process estimation by clinical data.</p>