Sit-to-walk (STW) motion is essential for daily activities. Falls frequently occur, when there is impaired ability to perform STW movements. This study investigated the relationships between the dynamical characteristics of STW motion and physical functions of elderly people. 128 elderly (51 males and 77 females, above 65 years) participated in this study. Participants were instructed to perform STW motion at comfortable state and classified into four groups (normal, mild, moderate and severe group) based on physical function, which evaluated with functional reach test and dynamic gait test. The results showed that some relationships were confirmed between the sample entropy characteristics of STW motion. Moreover, a subset of variables was significant different among four groups via Kruskal-Wallis test, which could be potentially used for developing an objective and simple methods to assess balance capacity and fall risk level of elderly people.