To save space in a sheet processing device even with a plurality of sheet processing means for conveying a sheet and processing an end surface of the sheet parallel to a sheet conveyance direction being arranged therein.

A sheet processing device includes: a clamp 401 for holding a deep end surface Pb of a sheet; a punch unit 270 and a staple unit 250 for applying a punching process on the deep end surface Pb side; a timing belt 403 in which a punching process section is provided at an above position thereof and a stapling process section is provided at an under position thereof, and for moving the clamp 401 to the both positions; a gear 405 and a boss 405a for retaining the clamp 401 in a pre-set attitude; and front and rear guide rails 406 and 407 provided on an outer periphery of a moving path of the timing belt 403, and for restricting the clamp 401 in conjunction with movement of the timing belt 403 to control the retained attitude thereof.