Sheet metal working machine comprising a hydraulic drive system suitable to drive a plurality of working tools (51, 151, 61) of said machine in a separate and independent manner to perform respective machinings on a piece, said hydraulic drive system comprising: - a plurality of hydraulic cylinders (2, 102, 202), each hydraulic cylinder (2, 102, 202) being associated with a respective working tool (51, 151, 61) and provided with a respective piston (21, 121, 221) suitable to define a thrust chamber (22, 122, 222) and a return chamber (23, 123, 223) inside the hydraulic cylinder (2, 102, 202) and associated with the corresponding working tool (51, 151, 61) for moving the latter along a respective working axis (A, B, C); - a first pump of reversible type connected to said thrust chambers (22, 122, 222) of said hydraulic cylinders (2, 102, 202) and arranged to send fluid at a supply pressure (P A) at least in one of said thrust chambers (22, 122, 222) in a driving phase so as to push the respective piston (21, 121, 221) along a working direction and enable the working tool (51, 151, 61) associated therewith to interact with the piece, or to suck fluid from at least said thrust chamber (22, 122, 222) in a return phase, to enable the respective piston (21, 121, 221) moving along a return direction and said working tool (51, 151, 61) disengaging and moving away from said piece; - a plurality of valves, each valve being associated with a respective hydraulic cylinder (2, 102, 202), interposed between said first pump and the thrust chamber (22, 122, 222) of the hydraulic cylinder (2, 102, 202) and activable to put into flow connection the first pump with the thrust chamber (22, 122, 222) so as to drive the hydraulic cylinder (2, 102, 202); - a hydraulic accumulator connected to said return chambers (23, 123, 223) of said hydraulic cylinders (2, 102, 202) and arranged for maintaining fluid at a defined preload pressure in said return chambers (23, 123, 223), in particular for moving along the return direction at least one piston (21, 121, 221) of a hydraulic cylinder (2, 102, 202) driven by activating the corresponding valve. - a plurality of hydraulic cylinders (2, 102, 202), each hydraulic cylinder (2, 102, 202) being associated with a respective working tool (51, 151, 61) and provided with a respective piston (21, 121, 221) suitable to define a thrust chamber (22, 122, 222) and a return chamber (23, 123, 223) inside the hydraulic cylinder (2, 102, 202) and associated with the corresponding working tool (51, 151, 61) for moving the latter along a respective working axis (A, B, C); - a first pump of reversible type connected to said thrust chambers (22, 122, 222) of said hydraulic cylinders (2, 102, 202) and arranged to send fluid at a supply pressure (P A) at least in one of said thrust chambers (22, 122, 222) in a driving phase so as to push the respective piston (21, 121, 221) along a working direction and enable the working tool (51, 151, 61) associated therewith to interact with the piece, or to suck fluid from at least said thrust chamber (22, 122, 222) in a return phase, to enable the respective piston (21, 121, 221) moving along a return direction and said working tool (51, 151, 61) disengaging and moving away from said piece; - a plurality of valves, each valve being associated with a respective hydraulic cylinder (2, 102, 202), interposed between said first pump and the thrust chamber (22, 122, 222) of the hydraulic cylinder (2, 102, 202) and activable to put into flow connection the first pump with the thrust chamber (22, 122, 222) so as to drive the hydraulic cylinder (2, 102, 202); - a hydraulic accumulator connected to said return chambers (23, 123, 223) of said hydraulic cylinders (2, 102, 202) and arranged for maintaining fluid at a defined preload pressure in said return chambers (23, 123, 223), in particular for moving along the return direction at least one piston (21, 121, 221) of a hydraulic cylinder (2, 102, 202) driven by activating the corresponding valve.