To provide an inexpensive sheet feeder having excellent separability.

In a sheet feeder which sucks a highest paper sheet of loaded paper sheets by an air suction belt means 11 having a vacuum chamber 14, and feeds the paper sheets by separating them one by one by an air nozzle means 7, the air suction belt means 11 is arranged in an inclined manner so that its suction surface is separated from the paper surface of the paper sheet S downstream of the feeding direction of the paper sheet S, the vacuum chamber 14 has a turning support point upstream of the feeding direction of the paper sheet S, the suction surface of the air suction belt means 11 is supported in an oscillating manner at the approaching position parallel to the paper surface of the loaded paper sheet S and at the feeding position to feed the paper sheet S away from the paper surface, and the vacuum chamber 14 sets the approach/ separation to/from the paper surface of the paper sheet S by a driving means 16.