Investigating the lack of trust in the contemporary society, researchers tend to use various definitions of trust in their social and cultural studies. Hence difficult is to compare the results of such surveys and to understand the essence of the studied phenomenon clearly. In this regard, the search for the fundamental sense of trust seems to be an urgent task. However, philosophical literature allows to conclude that the category was used as something obvious throughout the history of thought. Philosophers appeared to focus on analyzing phenomena either opposite (lie and deceit), or related but not identical (faith, fidelity, certainty, etc.). Thus, this study is reasonable at the ontological level, using hermeneutic and existential analysis, as a result of which, on one hand, it is possible to show the relation between trust and etymologically related truth, and, on the other hand, to understand its nature and to formulate a definition that reflects it’s basic sense. Trust is designated as a “switch” into the mode of openness to the light of truth, which does not change either words or state of affairs, but allows to check our own constructs for falsity and unproductiveness. Therefore, trust is offered to be studied not as a characteristic of the relationship to others: the basic background of any relationship is found to be the opening of human being to the “level” of truth as the full scale of reality. In this light, the article demonstrates the existential aspects of trust giving examples of life situations and investigates fears that lead to mistrust. Some recommendations are also formulated for overcoming these fears and for building the most reliable, non-conflict, trustworthy relationships.