| 摘要 |
A bearing member engageable and disengageable from a recessed portion of an image forming apparatus body is included. While the bearing member is engaged into the recessed portion, a cross-sectional area occupancy ratio which is a degree of area occupied by a cross-section of the bearing member to a cross-section of the recessed portion is 15% or higher and 75% or less. An outer peripheral shape of the bearing member in a cross-section is a hexagon, and assuming that a radius of a circumscribed circle of the hexagon is r1g, and when a hexagon is formed by sides enclosed by a triangle formed at an opening of the recessed portion when the recessed portion is viewed from a front in the axial direction and a triangle formed at a bottom of the recessed portion, a radius of an inscribed circle of the hexagon is r2h, r1g−r2h>0. |
