To enhance uniformity within a wafer surface in a device for manufacturing a semiconductor, and reduce the running cost of the device.

The circumference of abrasive cloth 2 coming in contact with the center part of a wafer, is kept at vacuum while the wafer is being polished, and a filter for polishing liquid and a valve 17 are mounted to a place underneath a turntable 4. The application of vacuum through the lower part of abrasive cloth 2 thereby allows polishing liquid to be deeply soaked in as far as the center part of the wafer so as to let its polishing condition be made constant, so that uniformity within a wafer surface can be enhanced. In addition, used polishing liquid having been sucked in by means of vacuum is filtered by a filter so as to be reused, so that cost can be reduced.