Unmanned construction is a construction method of operating construction machines from a remote place by using radio waves. In Japan, unmanned construction has many applications in disaster sites where people can not enter. However, unmanned construction is less than half of the construction efficiency as compared to normal boarding operations. We need to improve construction efficiency of unmanned construction. In normal unmanned construction, the operator mainly operates construction machines while looking at the image of the boarding camera installed in the cabin. However, visual information such as angle of view of images taken by boarding cameras is smaller than actual boarding conditions, which is considered to be one of the factors that lowers the work efficiency of unmanned construction. Therefore, it is necessary to consider a new camera system that can acquire visual information equivalent to boarding status. However, the detail range of field of view and the gaze target in boarding conditions have not been clarified. In this study, we measured the line of sight of the operator in boarding operations using the eye-mark recording system. From the results, we examined the field of view and the gazing target in boarding condition.