A printing device includes a printing cassette, and a platen roller. The printing cassette includes: a print tape; an input part into which a drive force is to be inputted; an output part rotatable about a rotational axis extending in a first direction; a transmission mechanism for transmitting the drive force from the input part to the output part; and a case. The case houses therein at least a part of the print tape, at least a part of the input part, at least a part of the output part, and at least part of the transmission mechanism. At least a part of the output part is positioned outside the case. The output part is positioned inside an outer edge of the case in a projection view where the output part and the case are projected onto a plane perpendicular to the first direction.