PURPOSE: To provide a press brake by which the superior bending is attained by compensating the change of the lower limit position caused by temperature change and pressurizing force difference of hydraulic oil.

CONSTITUTION: A work W is bent by relatively moving an upper die (one metallic die) 19 freely attachably/detachably provided on a ram 17 which is freely vertically moving by a hydraulic circuit and a lower die (another metallic die) 13 freely attachable/detachable provided on a frame (main body of the press brake) 3. A lower limit positioning valve (limitation positioning valve) 27 by which the hydraulic circuit is controlled is provided on the frame 3 to limit the amount of stroke of the ram 17 when the upper and lower dies 19 and 13 get near each other and an extention shaft (dog) 87 whose vertical position is freely adjusted by a compensating unit 55 is provided on the ram 17. Thus, since the minimum distance between the upper and lower dies 19 and 13 is fixed, the bending having a fixed angle is uniformly executed.