A printing device includes: a print head; a platen roller positioned to face the print head; a motor configured to generate a driving force to rotate the platen roller; a cassette receiving portion; and a power transmission portion configured to transmit the driving force of the motor to the platen roller. A cassette incorporating a printing tape to be printed by the print head is detachably attachable to the cassette receiving portion in a first direction. The power transmission portion includes a plurality of gears including a first gear movable from a first position to a second position downstream of the first position in the first direction. The power transmission portion is configured to switch a ratio of a rotation number of the platen roller to a rotation number of the motor depending on whether the first gear is at the first position or at the second position to transmit the driving force to the platen roller.