To provide a polishing pad in which clogging hardly occurs and the variation of polishing performance is reduced in the field of polishing, in particular, in a CMP process.

A foam plastic sheet having long air bubbles arrayed in the same direction is manufactured as follows. As raw material plastic, a thermoplastic polyurethane elastomer (produced by DAINICHISEIKA Color and Chemicals MFG. Co,. Ltd.) is used and carbon dioxide and the raw material plastic are mixed in a first extruder. Resin pressure in a mixing zone is 25 MPa, a resin temperature is 200°C, and the carbon dioxide is in a supercritical state. The cross section of the sheet is observed along with an MD direction by an electron microscope. As a result, an average minor axis length is 24 μm, an average major axis length is 50 μm and an aspect ratio is 2.1.