Support member, image carrier, and image forming apparatus

A support member supported in a cylinder includes six or more contact portions that are in contact with an inner peripheral surface of the cylinder. The support member is arc-shaped and has a gap extending in an axial direction of the cylinder. When the support member is viewed in the axial direction, a groove is formed in the support member such that the groove and the gap are on opposite sides of a center of the cylinder, and the contact portions are symmetrical with respect to a straight line that passes through the centers of the gap and the cylinder. Of the contact portions on one side of the straight line, the farthest contact portions are separated from each other by approximately 90 degrees or more, and the adjacent contact portions are separated from each other by approximately 20 degrees or more in the circumferential direction.