Medium carrying device and image forming apparatus

A medium carrying device that carries a medium, which is flexible, in a carrying direction along a carrying path from an upstream side to a downstream side, comprising:

• a first roller that is rotatable and located at the carrying path to carry the medium along the carrying path, the first roller being an idle roller;
• a second roller that is rotatable, located at the carrying path and at the downstream side from the first roller in the carrying direction, the second roller driving its rotation by a first driving force transmitted from a first driving force source;
• a rotation transmitting part that drives its rotation by a second driving force transmitted from a second driving force source, and moves between at a transmitting position and at a releasing position,
• at the transmitting position, the rotation transmitting part is positioned close to the carrying path in a perpendicular direction with respect to the carrying direction, contacting the first roller, and transmitting the second driving force to the first roller so that the first roller is driven by the second driving force,
• at the releasing position, the rotation transmitting part is positioned distant from the carrying path in the perpendicular direction with respect to the carrying direction, not contacting the first roller so that the first roller is not driven by the second driving force,
• a transmission releasing part that is positioned between the first and second rollers in the carrying direction, being connected to the rotation transmitting part, wherein
• when the medium is bowed between the first and second rollers, the transmission releasing part moves the rotation transmitting part from the transmitting position to the releasing position according to the bowing of the medium.