A rotatable tape guide with a cylindrical barrel having a cylindrical peripheral surface; and a guide flange substantially at each outer side of the cylindrical barrel and having a frusto-conical surface. The frusto-conical surface is configured at a taper angle outward with respect to the perpendicular direction from the cylindrical surface; the taper angle of the guide flange substantially at an angle such that the angle at which a tapered tangential line extends from the circumference of the cylindrical peripheral surface of the cylindrical barrel and along the taper of the guide flange, to the maximum periphery of the frusto-conical surface, is at the maximum potential angle of attack from a magnetic tape at a supply reel with respect to the guide flange.