To provide a sheet sorting apparatus effectively preventing the rear end of a sheet from being left behind whereby a stable stacking performance can be attained, and to provide an image forming apparatus provided with it.

The sheet sorting apparatus 120 for sorting the sheet P placed on a sheet discharging tray 91 from a sheet conveying part 30 by shift movement of the sheet conveying part 30 conveying the sheet P in a shift direction X is provided with a sheet-presser guide 300 for pressing the sheet P by coming into contact with the sheet P placed on the sheet discharging tray 91. The sheet-presser guide 300 is provided with a contact member 310 coming into contact with the sheet P discharged to the sheet discharging tray 91. The contact member 310 is configured in a manner that a friction force acting on the sheet P sliding down a slope of an inclined surface 91a toward the upstream side in the conveying direction Y1 is larger than a friction force acting on the sheet P upon movement of the sheet-presser guide 300 in the shift direction X.