To provide a polishing body capable of dressing, by solving a problem that in-situ-measuring can not be done since a polishing body (polishing pad) is shaved and the surface of a window on the object side to be polished is injured and becomes optically opaque at the same time when dressing, in the case of a conventional polishing body.

This polishing body has one or more opening parts and windows installed at the opening parts. The surface of the window on the object side to be polished is recessed and the recessed quantity is gradually or continuously changing. Thereby, a polishing condition can be excellently in-situ-measured by switching to a window or a part of the window having no injury when a whole or a part of the surface of the window on the object side to be polished is injured by dressing.