The Indian and Tibetan traditions of definition of Four Noble Truth taught by Buddha Shakyamuni are analyzed. The author comes to the conclusion that the formulations of Four Noble Truths as «truths about …» found in the Russian literature on the Buddhism are their interpretations in keeping with the European gnoseology, which is incorrect. Since the primary and basic meaning of Four Noble Truths is ontological rather than gnoseological. On the basis of the Tibetan sources three levels of Buddha’s idea of Four Noble Truth are identified and described.