An expanding apparatus for expanding an expansion sheet to which a workpiece including at least a ductile material is adhered. The expanding apparatus includes expanding means for expanding the expansion sheet. The expanding means includes a plurality of moving units that are each configured and arranged to move an associated holding unit, and wherein each of the holding units is configured and arranged to clamp and hold a portion of the expansion sheet. The apparatus also includes cooling/heating means with a plate having a contact surface for contacting the workpiece, and a Peltier element for cooling or heating the plate. Finally, the apparatus includes a polarity change-over means for changing over the polarity of current passed to the Peltier element, wherein the polarity change-over means is configured and arranged to be switched between one status in which the plate is cooled and another status in which the plate is heated.