A sheet feeder includes; a sheet feed roller that abuts against a topmost sheet of stacked sheets and rotates to convey the topmost sheet in a conveyance direction; an arm spanning across a drive shaft and the sheet feed roller; a rotating transmission member that transmits rotation of the drive shaft to the sheet feed roller, wherein the arm is provided with a cantilever shaft that supports the rotating transmission member, and an elastic member that faces an end face of the rotating transmission member to retain the rotating transmission member in the cantilever shaft.