Abstract: With a time control means for a wetting treatment of a fixed abrasive platen provided, the fixed abrasive platen is set in a good wet state in advance prior to the start of polishing. The time control means may be incorporated in the body of a flattening/machining apparatus, or alternatively a wetting retaining mean may newly be separately provided instead. While the fixed abrasive platen is rapidly transformed through expansion due to wetting, the wetting treatment is desirably performed till a transformation ratio thereof is stabilized at 0.0005% or less.