A sheet feeder, including: a holding portion for holding sheets; a sheet supply portion; an inclined member having an inclined surface for guiding each sheet in a sheet feed direction along the inclined surface; a first separation protrusion provided integrally on the inclined member so as to protrude from the inclined surface such that its distal end is located more downstream in the sheet feed direction than its proximal end; a plurality of second separation protrusions formed of a metal and disposed more upstream in the sheet feed direction than the first separation protrusion, each second separation protrusion protruding from the inclined surface through a corresponding one of openings formed in the inclined member, the second separation protrusions being arranged in the sheet feed direction; and a fixing member by which the second separation protrusions are fixed to the inclined member on a surface thereof opposite to the inclined surface.