A recording tape cartridge houses a reel including a hub around which recording tape is wound and at least part of which is formed by a resin. The rigidity (modulus of elasticity) y in the radial direction of the hub and the creep deformation ratio x of the recording tape satisfy the conditions of y≧87.3 exp(21.6x) and x>0.1. By setting the rigidity of the reel hub to match the creep deformation ratio of the recording tape so as to satisfy this relationship, creep deformation of the recording tape can be controlled at the smallest cost.