Note that the housing 60 ismade of stainless steel; however, it may be made of metal such as steel, copper alloy, nickel alloy, or chromium alloy.The housing 60 is provided with the fluid passage 6 for supplying the supply fluid H for a polishing solution, which passes from an outer circumferential surface thereof to the space (also referred to as the vacant space) 62C. Also, in aposition on the f