A sheet feeding apparatus, having: a sheet stacking table to stack sheets; a sheet feeding device to feed the sheets one by one from an upper most section of the sheets stacked on the sheet stacking table; an assist air blower device to blow an assist air at a lateral side, a front side or a rear side of the sheet fed from the sheet stacking table so as to assist sheet feeding; a detecting device to detect a behavior of the sheet assisted by the assist air; and a control device to set an amount of the assist air used in image forming to be an optimum air amount based on a detected result which is obtained by detecting the behavior of the sheet when the assist air blower device is operated at a predetermined timing while image forming is not carried out.