The present invention aims to provide a tape cartridge which enables the movement of an engagement position between a ribbon paying-out core and a paying-out-side driving shaft to the outside in a radial direction without enlarging a ribbon taking-up core in the radial direction. The tape cartridge is provided with: the ribbon paying-out core 42 on which an ink ribbon R is wound so as to be capable of being paid out; and a ribbon taking-up core 43 that takes up the ink ribbon R paid out from the ribbon paying-out core 42. The ribbon paying-out core 42 has a core body 81 that winds the ink ribbon R, and a coronary engagement part 82 that is formed at an end of the core body 81 and engages a paying-out-side driving shaft 34 of a tape printer 1. The coronary engagement part 82 protrudes in an axial direction from an end surface of the core body 81 and is formed in a coronary shape in which a plurality of convex parts 82a and concave parts 82b are alternately arranged side by side in a circumferential direction.