—In this paper, we propose a novel concept of Ubiquitous Virtual Reality (U-VR) and examine technical challenges to be required for realizing it. It is difficult to realize Virtual Reality (VR) in our daily life although a lot of hardware and software have been developed. In addition, there is no chance for people to experience VR systems except for a special exhibition since there is no attractive application. On the other hand, there is extensive research regarding the possible applications that support the user’s interaction, utilizing various aspects of context of the user and the ubiquitous computing environment which will be equipped with many pervasive but invisible computing resources. Thus, we present a concept of U-VR that is realized through the feature of Collaborative Wearable Attentive MR (Mediated Reality). Also, we investigate three challenges that are significant in realizing U-VR in holistic u-Space.