An image forming apparatus includes an engagement piece, connected to a cylindrical member at a crease which extends in a direction crossing a circumferential direction of the cylindrical member, projecting radially outward from the cylindrical member. The engagement piece may engage with a gear to prevent the gear from detaching from the cylindrical member. In addition, the cylindrical member may include a concave portion to engage with a convex portion of the gear. Also, the gear may include a cover portion that includes a communication hole through which a tool may be inserted in order to configure the engagement piece.