To improve the punching position accuracy of a sheet by reducing the amount of deviation from a determined position.

A sheet processing device includes: a sheet punching device 200 for punching a hole in a sheet by charging or discharging a punch 230 into or from a die hole 210c of a rotating die 210; and a conveying roller pair 311 for holding the sheet by a nip NP to convey the sheet to the sheet punching device. The charged and discharged position of the punch into or from the die hole of the sheet punching device and the nip of the conveying roller pair are located on a plane orthogonal to the conveying direction of the sheet. Thus, the conveying roller pair is located at the side the sheet punching device, the sheet punching device punches a hole in a part in which the conveying roller pair conveys the sheet without generating any loop on the sheet, and thus the sheet is punched by reducing the amount of deviation from a determined position.