The invention relates to a monitored roller bearing device, comprising a non-rotating race (10), a rotating race (12), at least one row of rolling elements (14) arranged between two rolling tracks (11, 13) on the rotating race (12) and non-rotating race (10) and an information detection module, which comprises a non-rotating sensor unit (29) and a rotating (12) encoder (28). Said device comprises a means for fixing the sensor unit (29) relative to a support (3), by generating an axial force between a support surface (34b) on the sensor unit (29) and a support surface (7) on the support (3), while permitting an axial displacement of the sensor unit (29) relative to the support (3).