A sheet feeding apparatus includes a sheet supporting portion, a sheet feeding portion configured to feed a sheet supported on the sheet supporting portion in a sheet feeding direction, an air blow unit including an air blower, an opening portion, a duct configured to form a flow path through which air flows, an adjustment portion configured to vary an opening dimension, the air blow unit being configured to separate a plurality of sheets, including an uppermost sheet, a drive source configured to drive the adjustment portion, and a control unit configured to execute a first mode in which the drive source is controlled such that the opening dimension is set to a first dimension, and a second mode in which the drive source is controlled such that the opening dimension is set to a second dimension that is smaller than the first dimension.