Sustainable development goals (SDGs) have attracted considerable attention in recent years. In Japan, “Society 5.0” has been proposed and promoted by various organizations as a vision for a future society linked to achieving these SDGs. Particularly, “i-Construction” has been promoted in the construction industry. For example, hydraulic excavators are automated (or semi-automated). Nevertheless, having a sense of accomplishment and motivation for the work through active operations is important for operators. In this study, a control system that automatically adjusts the operational assistance rate according to the user is proposed. Modeling a person is difficult because they exhibit time-varying and nonlinear characteristics. Therefore, the control system uses work data to evaluate the differences in the desired characteristics and adaptively adjusts the operational assist rate. The proposed method was implemented on a hydraulic excavator and its effectiveness was verified.