The paper is aimed at the category of unreliability of the narrative text. The author builds on narratological works which consider fictional and historical texts as different types of narratives. Essential difference can be identified in the sphere of reference of these texts and in both basic levels of common narratological model of analyses – in the level of discourse and story. The paper presents a set of mutually linked differences as a border between two different contexts of “unreliability”. Quotation marks express an opinion that narrator’s unreliability (theoretically elaborated in connection with fictional narrative) cannot be analogically applied in analyses of “unreliable narration” in historical text. After a brief summary of parallel aspects of narrativity, the author pays attention to giving reasons for two different regimes of “unreliability” as well as to selection of suitable terminology.