Abstract: A tape reel having a cylindrical tape winding face on which magnetic tape is to be wound, and upper and lower flanges formed at upper and lower ends of said tape winding face. Grooves (20), which are designed to discharge to the outside the air interposed between portions of the magnetic tape that is wound on a tape winding face (8), are provided in the surface of the lower flange (9) which contacts the magnetic tape. The dimensions of each part are set so that the opening area of the grooves (20) lying within the tape winding range (21) where the magnetic tape is wound is 30 percent (standard value) or more relative to the total area of the tape winding range (21). By this structure, even in the case where the magnetic tape is wound at high speed on the tape winding face (8), the air interposed between portions of the magnetic tape is rapidly discharged to the outer periphery through the grooves (20), and the winding attitude is good.