A tape cartridge is detachably installed on a cartridge installation portion of a tape printing apparatus having a platen supporting shaft and a printing head. A base end of the platen supporting shaft is fixed to the cartridge installation portion at one end of the platen supporting shaft. The tape cartridge includes the platen roller, the upper bearing portion, the lower bearing portion, and the fitting portion. The platen roller includes an upper and lower engagement portion. The upper bearing portion rotatable supports the upper engagement portion and restricts movement of the upper engagement portion. The lower bearing portion rotatable supports the lower engagement portion and restricts movement of the lower engagement portion. The fitting portion in which a tip end of the platen supporting shaft passing through the platen roller fits when the tape cartridge is installed on the cartridge installation portion.