The invention relates to a belt tensioner (1) for a belt drive for auxiliary units in an internal combustion engine, comprising a tensioner housing (2), a tensioner lever (3) and a plain bearing for radially mounting the tensioner lever (3) in the tensioner housing (2) in such a way as to allow the tensioner lever (3) to swivel; a bearing partner associated with the tensioner lever (3) is in sliding contact with a second bearing partner associated with the tensioner housing (2); one of the two bearing partners is suspended in a radially elastic manner on the associated part that supports said bearing partner in a rotationally fixed manner.