A workpiece clamping jig configured to clamp a workpiece is provided with a baseplate, a fixed abutting member, and a movable abutting member. The baseplate has a pocket, which forms an air intake passage on the reverse side of a workpiece mounting surface, and a suction through-hole internally connecting the workpiece mounting surface and the pocket. The fixed abutting member is disposed on the baseplate and has a fixed abutting surface corresponding to the shape of the workpiece, and the movable abutting member has an abutting surface movable relative to the workpiece caused to abut against the fixed abutting surface of the fixed abutting member.