A sheet processing apparatus including: a cutting mechanism, the cutting mechanism being configured to cut a sheet in a direction orthogonal to a sheet conveying direction by upper and lower cutting blades (22A, 22B) on the opposite sides of a sheet conveying surface, a pair of first conveying rollers arranged on the sheet conveying upstream side of the cutting mechanism and configured to feed the sheet to the cutting mechanism, and a pair of second conveying rollers arranged on the sheet conveying downstream side of the cutting mechanism, characterized in that the sheet processing apparatus includes: driving sources (43, 44, 50) configured to independently drive the pair of first conveying rollers, the pair of second conveying rollers, and the cutting mechanism, and a control section configured to control the operation of the driving source (43, 44, 50), in which when sheet conveying direction length (Lr) of rear end cut region (Sr) of the sheet is equal to or more than predetermined value (Dn), rear end cut region (Sr) is sequentially cut and divided into predetermined fine-cutting unit length from the sheet conveying downstream end thereof, wherein the control section is configured to control the driving sources (43, 44, 50) so that sheet conveying direction length of rearmost end divided region in rear end cut region (Sr) is the length substantially corresponding to distance between cutting position of the cutting mechanism and nipping position of the pair of first conveying rollers and that when rearmost end divided region passes through the nipping position of the pair of first conveying rollers, the pair of first conveying rollers are rotated 90° or more. a cutting mechanism, the cutting mechanism being configured to cut a sheet in a direction orthogonal to a sheet conveying direction by upper and lower cutting blades (22A, 22B) on the opposite sides of a sheet conveying surface, a pair of first conveying rollers arranged on the sheet conveying upstream side of the cutting mechanism and configured to feed the sheet to the cutting mechanism, and a pair of second conveying rollers arranged on the sheet conveying downstream side of the cutting mechanism, characterized in that the sheet processing apparatus includes: driving sources (43, 44, 50) configured to independently drive the pair of first conveying rollers, the pair of second conveying rollers, and the cutting mechanism, and a control section configured to control the operation of the driving source (43, 44, 50), in which when sheet conveying direction length (Lr) of rear end cut region (Sr) of the sheet is equal to or more than predetermined value (Dn), rear end cut region (Sr) is sequentially cut and divided into predetermined fine-cutting unit length from the sheet conveying downstream end thereof, wherein the control section is configured to control the driving sources (43, 44, 50) so that sheet conveying direction length of rearmost end divided region in rear end cut region (Sr) is the length substantially corresponding to distance between cutting position of the cutting mechanism and nipping position of the pair of first conveying rollers and that when rearmost end divided region passes through the nipping position of the pair of first conveying rollers, the pair of first conveying rollers are rotated 90° or more. driving sources (43, 44, 50) configured to independently drive the pair of first conveying rollers, the pair of second conveying rollers, and the cutting mechanism, and a control section configured to control the operation of the driving source (43, 44, 50), in which when sheet conveying direction length (Lr) of rear end cut region (Sr) of the sheet is equal to or more than predetermined value (Dn), rear end cut region (Sr) is sequentially cut and divided into predetermined fine-cutting unit length from the sheet conveying downstream end thereof, wherein the control section is configured to control the driving sources (43, 44, 50) so that sheet conveying direction length of rearmost end divided region in rear end cut region (Sr) is the length substantially corresponding to distance between cutting position of the cutting mechanism and nipping position of the pair of first conveying rollers and that when rearmost end divided region passes through the nipping position of the pair of first conveying rollers, the pair of first conveying rollers are rotated 90° or more.