In this paper, two empirical studies, 'pointing task'and 'assembling task'are conducted in order to compare HMD with 40 inch projector as a display device for direct manipulation in a virtual workspace. In 'pointing task, 'it was shown that 40 inch projector was preferred to HMD with relatively small workspace, while HMD was preferred to 40 inch projector with relatively large workspace. In 'assembling task, 'it was shown that HMD was preferred to 40 inch projector even with small workspace.
