We focus on a shared augmented environment (SAE) as an almost ideal face-to-face collaborative virtual workspace. In an SAE, multiple users can observe both a virtual world and real partners through optical see-through head mounted displays. This paper describes two experiments for verifying the effectiveness of an SAE compared with a conventional shared virtual environment (SVE) and exploring improvement of them. Through the experiments, the effectiveness of an SAE compared with an SVE was confirmed. It was also confirmed that enhancement of the shared environment with computer graphics, i.e. displaying a partner's body in an SVE, drawing a linear as a partner's viewing directions and emphasizing virtual objects to which a partner pay attention, improves workers' feeling and collaboration efficiency.