The article presents the author's theory of consciousness. The proposed theory allows describing unexplained yet psychological phenomenology. Ideal (psychic) and material (physical) is viewed as attributes of the substance-process of activity. Human is the subject of not one activity, but of the integral system of activities. Thus, individual consciousness is the attribute of individual system of activities and personal history of activities of the person. The difference between a system and a history of every man causes differences of consciousness (ideal attribute of system of activities) and corporeality (material attribute). Group differences of the systems of activities cause, accordingly, cultural, ethnic, regional, professional and other group differences of attributes of activity (of consciousness and corporeality). We change reality with our activity, i.e. reality is partly dependent on our activity. Thus, “objective reality, which is independent of our consciousness” and our acts, is non-existent, and taking into account consistency and interconnectedness of the Universe, this redefines the issue of responsibility of the subject of the conscious process. Various states of consciousness of man gather in one integral self-consciousness with the help of his continuous and developing system of activities. New states of consciousness (and new knowledge) are born not from the consciousness itself, but from the development of one’s activity. Joint activity causes joint consciousness (ideal attribute of joint activity) and joint corporeality (instrumentality material attribute). Inclusion of various subjects in common activity causes transpersonality (in its limit – noospherity) of consciousness. The unexplained yet by science, but stated parapsychological phenomenology is possible to study with the schemes of structures of individual and joint activity as processes and products of these activities, as results of processes of transpersonality and continuity (skandhas) of activities.