Rotation device

The project of the invention is to obtain a rotation device which can further improve lubricity of oil seal. A reduction gear is the rotation device (12), comprising a housing (34) which is sealed with a lubricant, the housing being a cover housing (54), an input shaft (18), and oil seal (72). The oil seal is configured on the axial outer side which is closer to the input shaft than an input bearing (60). Axial movement of the input bearing is limited by a check ring (74). The check ring is embedded in a check ring groove (54A) on the inner side which is closer to the reduction gear than the position of the input bearing. The housing is provided with a lubricating channel (78) on the radial outer side of the input bearing. The lubricating channel communicates a space which is closer to the inner side of the reduction gear than the input bearing and the oil seal. The lubricating channel is provided with an inclined surface (78D) which is inclined relative to the input shaft. the tail end (78D2) of the inclined surface is closer to the oil seal side on the axial direction than the position of the check ring.