Abstract: A device for monitoring wear of a flange (1) of a roller (2) includes a peripheral rim (3) and intended to cooperate with a homologous flange (1bis) of a roller (2bis) positioned face-to-face to interact with the head of a rolling rail (4). The device includes at least one first recess localized at the level of a peripheral line of constant radius on the flange (1) configured to be positioned at the level at which the point (7) of separation of the flange (1) relative to its homologue (1bis) is the smallest.