To securely separate and feed a thin sheet or a thick sheet by preventing error of sheet set while ensuring excellent paper handling.

This sheet feeding device feeds a sheet loaded on a sheet loading member by a feeding rotary body and separates sheets from each other by crossing a butting member on which a fed sheet is butted and whose angle is elastically changed. This sheet feeding device has a mountable guide member. When a sheet guide member is mounted on the sheet feeding device, a position where a sheet is abutted on the butting member is changed when the sheet guide member is not mounted on the sheet feeding device. When a sheet is set, a leading end of sheet is abutted on an upper end of the butting member or a position lower than the upper end. When feeding sheet, the sheet guide member is elastically deformed and is curved so that the leading end of sheet crosses the butting member.