Image reading device

An image reading device comprising:

• a medium supporting portion that supports a medium to be fed;
• a curved inversion route in which the medium fed from the medium supporting portion is curved and inverted;
• a reader that reads the medium having passed through the curved inversion route;
• a transportation roller that is disposed in the curved inversion route and transports the medium to the reader;
• a discharging roller that is provided on a downstream side of the reader and discharges the medium read by the reader;
• and
• a power transmission unit that transmits power of a driving source to the transportation roller and the discharging roller,
• wherein the power transmission unit is configured to include a plurality of gears,
• wherein the plurality of gears include
• an input gear that is provided at a branching position at which a power transmission route branches into a first power transmission route towards the discharging roller side and a second power transmission route towards the transportation roller side and that transmits the power of the driving source to the first power transmission route and the second power transmission route,
• a first gear group that constitutes the first power transmission route, and
• a second gear group that constitutes the second power transmission route and that is configured to include a smaller number of gears than the first gear group,
• wherein the second gear group includes a transportation roller driving gear that is provided on a rotation shaft of the transportation roller and is disposed inside the curved inversion route as seen from an axial direction of the rotation shaft, and
• wherein at least a portion of the transportation roller driving gear is positioned inside a medium transportation region in a width direction of the medium.