A workpiece clamping device able to perform a set-up changing operation for clamping members depending on the kind of a workpiece to be processed, at a low cost, by a simple method. The workpiece clamping device includes a bracket, a movable part which is movable with respect to the bracket, a clamping member to be attached to and detached from the bracket or the movable part, to clamp a workpiece, and a detachable device for detachably coupling the bracket or the movable part to the clamping member.