Expanding method and expanding apparatus

An expanding method for expanding an expansion sheet to which a workpiece including at least a ductile material is adhered, the expanding method comprising:

• a plate cooling step of cooling a plate of cooling/heating means, which includes the plate having a contact surface for contact with the workpiece and a Peltier element for cooling or heating the plate, to a temperature to which to cool the workpiece;
• a workpiece cooling step of bringing the plate into contact with the workpiece through the expansion sheet to cool the workpiece, after the plate cooling step is performed;
• an expanding step of expanding the expansion sheet, after the workpiece cooling step is performed;
• a plate heating step of heating the plate, after the workpiece cooling step is performed;
• and
• a workpiece heating step of bringing the plate into contact with the workpiece through the expansion sheet to heat the workpiece, after the expanding step and the plate heating step are performed.