The present invention provides a sheet feeding apparatus having a sheet supporting tray removably mountable within the sheet feeding apparatus and adapted to stack and support sheets, a regulating device provided on the sheet supporting tray and adapted to regulate and position lateral edges of the sheets stacked in the sheet supporting tray, an urging mechanism for urging with a predetermined urging force the sheets stacked in the sheet supporting tray against the regulating device, and an urging force adjusting mechanism for adjusting the urging mechanism so that the urging mechanism can urge the sheets against the regulating device with greater force during insertion of the sheet supporting tray into the sheet feeding apparatus.