A polished-piece holder is provided that does not easily stick or adsorb to a polishing pad of a polishing apparatus and reduces occurrences of production line troubles and therefore the number of failed polished pieces. A single sheet of a thermosetting resin impregnated fiber substrate or a laminated sheet formed by laminating a plurality of sheets of the thermosetting resin impregnated fiber substrate is formed under heat and pressure into a plate. The thermosetting resin impregnated fiber plate is then processed to form a polished-piece holder for holding pieces to be polished. The evaluation portion has a certain length in a direction of the average line. The thermosetting resin impregnated fiber plate has a surface roughness with a maximum wave height Ry of 10 &mgr;m or greater over an almost entire area of the surface layer. The maximum wave height Ry is determined in an evaluation portion of a wave curve by summing a height Rp of a highest crest and a depth Rv of a deepest trough from an average line of the wave curve. The wave curve is taken from a cross-sectional curve obtained by the surface roughness measuring device.