This tape cartridge is provided with a tape reel being rotatable and having a reel teeth portion; and a brake-locking member having a brake teeth portion in which mating operation and mate-releasing operation can be performed with respect to the reel teeth portion. The reel teeth portion and the brake teeth portion, each has plural teeth. Each of the teeth has a taper portion being inclined toward both sides from a tip part of the taper portion and a vertical portion extending in a substantially vertical manner from both end terminals of the taper portion to a base portion. At the time of the mating, the tip part is contacted with a bottom surface of the base portion at the side of the opposite teeth, and the vertical portion is opposed to the vertical portion at the side of the opposite teeth. At the time of mating, the vertical portions of the teeth are mutually contacted and the mating state is hard to become unfitted. Additionally, height of the teeth can be low and a gap between the teeth can be wide when the cartridge is used, so that contact between the teeth can be prevented.
