A paper feeder includes a lift plate, a pickup roller, a feed roller, a retard roller, a rotation-count detection sensor, and a control unit. The rotation-count detection sensor outputs a rotation-count detection signal. The rotation-count detection signal indicates a rotation count of the retard roller. The control unit detects the rotation count of the retard roller based on the rotation-count detection signal. The lift plate separates from the pickup roller before the control unit detects the rotation count of the retard roller. The feed roller is driven when the control unit detects the rotation count of the retard roller. The retard roller is in abutting contact with the feed roller when the control unit detects the rotation count of the retard roller. The control unit determines whether replacement of the retard roller is necessary or not, based on the detected rotation count of the retard roller.