Reel and recording tape cartridge

摘要

A reel comprises a hub onto which recording tape is wound and a flange that is disposed on an end portion of the hub and retains a width-direction end portion of the recording tape, wherein plural cutout portions that locally divide the hub and the flange are formed in the flange. The cross section of the hub in plan view has a substantially equilateral triangular shape and positions where constricting force resulting from the tape reaches a maximum are caused to protrude in advance.