A unit (1) for bending sheet metal (38) comprises a bending press (2), a device (4) for manipulating the sheet metal (38), and an auxiliary gripping device (16) for turning the metal sheet through 180.degree. about an axis (D) perpendicular to the bending line (B) of the press (12). The auxiliary gripping device (6) includes a plurality of grippers (36). The grippers (36) are carried by a support (24) fixed to the base structure (8) of the press (12) above the manipulation space (MS) at a height so that, when the grippers are above the manipulation space (MS), the auxiliary device (16) does not obstruct access of operators to the press (2) if the press is used manually. A device (111) for manipulating sheet metal (222) for a bending press (444) includes a main device (100) which is slidable along a guide beam (160) fixed parallel to the bending line (J) of the press (444) and an auxiliary gripping device (240) for turning the metal sheet over about an axis (L) perpendicular to the bending line (J). The auxiliary gripping device (240) is carried by the main device (100) of the manipulator device (111) and the guide beam (160) has a flattened shape so that, when the manipulator device (111) is in an inoperative position at the side of the press (444), the auxiliary device (240) does not obstruct access to the press (444) and the guide beam (160) can be used as a platform by operators engaged in the manual manipulation of pieces of metal sheet.