Workpiece processing method

A workpiece processing method of processing a workpiece having division starting points formed within the workpiece along a plurality of intersecting planned dividing lines, and having a surface protective tape affixed to a top surface of the workpiece, or a workpiece divided into individual chips along a plurality of intersecting planned dividing lines, and having a surface protective tape affixed to a top surface of the workpiece, the workpiece processing method comprising:

• an affixing step of affixing an undersurface side of the workpiece onto an expanding sheet having a larger size than the workpiece;
• a preliminary expanding step of expanding the expanding sheet after performing the affixing step;
• a surface protective tape peeling step of peeling the surface protective tape off the top surface of the workpiece in a state in which the expanding sheet is expanded while the preliminary expanding step is performed;
• and
• an expanding step of expanding the expanding sheet by an amount of expansion, the amount of expansion being a value larger than an amount of expansion of the expanding sheet in the preliminary expanding step, after performing the surface protective tape peeling step.