A sheet feeder includes: a sheet feeding assembly including: a shaft having an insertion part; and a feed roller; and a main body including: a rotary part; and first and second bearings. The main body supports the sheet feeding assembly. The rotary part rotates upon transmission of a drive force and receives the insertion part. The bearings support the shaft. An opening of an open portion of the first bearing has a circumferential dimension greater than a diameter of the shaft. The shaft supported by the bearings is movable between a mounted position and a retracted position. The feed roller is supported by the shaft, and movable as the shaft moves between the mounted position and the retracted position. The insertion part is separated from the rotary part when the shaft is in the retracted position, and inserted into the rotary part to place the shaft in the mounted position.

A printing apparatus includes a printing portion for printing on a medium, a driving roller for transporting the medium, a first and a second driven roller which are respectively supported with a gap in one roller shaft in a shaft line direction of the roller shaft and rotate around the roller shaft while pressing the transported medium on the driving roller, and a shaft support member that has a shaft support portion which supports the roller shaft between the first driven roller and the second driven roller. The first and the second driven roller have a through hole into which the roller shaft is inserted and an inner diameter in a roller center portion is smaller than an inner diameter of a roller end portion in the shaft line direction. The roller shaft is supported so as to be swingable with the shaft support portion as a support point.

A medium discharge device includes a discharge driven roller that nips the medium between the discharge driven roller and a discharge drive roller and that rotates drivenly and a first discharge aid member and a second discharge aid member that have a larger diameter than the discharge driven roller and that rotate by torque from the discharge driven roller, wherein the second discharge aid member is positioned to the outside of the first discharge aid member in the width direction, and the torque from the discharge driven roller is transmitted to the second discharge aid member via a shaft and an universal joint.