The highest incidence of disaster at a construction site is about 33.1% and this disaster occurs when an excavator is operated in dangerous site that can have rollover, confinement, and fall. The development of unmanned excavator is realized briskly for the safety of the operator from these dangers. The system to operate an excavator from a remote can be divided into conversion and mounted type. We have implemented this research about a system that has advantages of conversion and mounted type. This system enables excavators to be unmanned and remotely controlled without any renovation, remodeling, change, or transformation by applying attachable and separable mechanism and modules and this proposed system has advantages of conversion and mounted type. The system had a problem of poor operation performance due to the workspace inconsistency between remote controller and lever control robot, which produced lower speed. To improve this problem, the workspace mapping between remote controller and the robot to operate the lever of an excavator is proposed to improve the workability of excavator that is operated from a remote in this paper.