To provide a polishing expanded sheet, which has less variation in polishing characteristic, high polishing accuracy, and is friendly to the environment, as an abrasive pad used for a surface smoothing process of a semiconductor device wafer, such as a inter-layer insulating film or metal wiring, and a manufacturing method for the polishing expanded sheet.

The polishing expanded sheet contains bubbles of an average diameter of 0.1 μm or more to less than 300 μm, which are formed with a foaming agent of gas that remains to be gas under ordinary pressure at ordinary temperature, and also contains abrasive grains. The gas remaining to be gas under ordinary pressure at ordinary temperature is made of carbon dioxide or nitrogen, or is mixed gas composed of both elements, and the main component of a material composing the sheet is desirably to be polyurethane.