Insufficiency of fiscal possibilities of taxation for fulfilment by state its functions cause budget unbalances, which manifest themselves in exceeding budget expenditures over receipts. In order to cover the budget deficit the government attracts state loans, which cause appearance and accumulation of the state debt. Development of efficient debt policy and mechanism of state debt administration requires its clear conceptualisation. To achieve this the article applies philosophic and semantic approaches for the study of the essence of the state debt. The use of the philosophic approach allowed the study of multi-aspect nature of the state debt through the prism of such correlative categories as "essence", "phenomenon", "content" and "form". Using the semantic approach the article differentiates "debt" and "indebtedness" notions. The article also studies definitions of domestic and foreign scientists, analyses them and offers a clarified definition of the state debt, which takes into account the multi-aspect nature of this notion.