Unmanned construction with remotely operated construction machines is actively used a means of construction work in dangerous areas with no access to people such as rehabilitation work sites damaged by natural disasters including earthquakes or volcano eruptions. Unmanned construction is expected to progress in the field as a quick and safe technique for restoration from disaster damage. However, unmanned construction with remotely operated hydraulic excavators is known to be much poorer in work efficiency than construction work with directly operated machines. The Public Work Research Institute (PWRI) has been promoting research on the actual status of, causes of, and solutions to reduced work efficiency of unmanned construction with remotely operated hydraulic excavators. Our research focused on the impact that different operation systems of a remotely operated hydraulic excavator had on the work efficiency with the aim of obtaining knowledge that will help improve the work efficiency of unmanned construction. To fulfil this purpose, a comparative experiment was conducted using a few operation systems with changed parameters of operation interface for a hydraulic excavator. The data obtained from the experiment were analyzed for each operation system and work element, with important points that express differences in work time and work efficiency analyzed for clarification. Causes that resulted in differences were also discussed using video records. Based on the experiment, the authors successfully clarified the status of the impact of interface operability for a remotely operated hydraulic excavator on the work efficiency and obtained knowledge that will lead to improved work efficiency of unmanned construction.