A sheet feeder, including: a sheet supply roller configured to supply a sheet to a sheet feeding path; a sheet feed roller configured to feed the sheet supplied to the sheet feeding path by the sheet supply roller to a downstream side in a sheet feeding direction in which the sheet is fed; a discharge roller configured to discharge the sheet fed by the feed roller to a downstream side in the sheet feeding direction; a drive motor configured to drive a first shaft for rotating the feed roller; a first transmitting mechanism configured to transmit a rotary motion of the first shaft to a second shaft for rotating the discharge roller; and a second transmitting mechanism configured to transmit a rotary motion of the second shaft to a third shaft for rotating the sheet supply roller.