A workpiece supply device for supplying a plate-shaped workpiece to a press brake, including: a slider movable along a Y-axis-direction guide member that is provided on a base frame movable in X-, Y-, and Z-axis directions relative to a press brake, the slider being capable of being positioned at an end of the guide member; and a workpiece holder provided on the slider and capable of holding a workpiece, wherein a part of the workpiece holder is capable of protruding from the end of the guide member.