The invention provides a medium and a tape cartridge. The medium includes a transparent base layer and a separation layer stacked on each other. A plurality of regions are defined in the medium alonga first direction orthogonal to the stacking direction, wherein the plurality of regions comprise: a first region in which a portion of the medium which is in contact with the separation layer is stickable; a second region which is located on one side of the first region in the first direction and in which a portion of the medium which is in contact with the separation layer is non-stickable; anda third region which is located on the one side of the second region in the first direction and in which a portion of the medium which is in contact with the separation layer is at least partly stickable. Four first vertexes located on an outer shape of the first region so as to serve as four corners of a first imaginary trapezoid shape and four second vertexes located on an outer shape of the third region so as to serve as four corners of a second imaginary trapezoid shape are symmetric with respect to an axis parallel with a second direction orthogonal to each of the first direction and thestacking direction. The medium is attachable rotatably around a wrapped member without additional force. The tape cartridge accommodates the medium.