Provided is a water absorbent sheet retaining mat which can retain a water absorbent sheet easily and surely. A water absorbent sheet retaining mat M1, M2, M3, M4 for retaining a water absorbent sheet Sa1 having a first polygonal contour, comprises: a mat member Pm1, Pm2, Pm3, Pm4 having a second polygonal contour defined by mutually opposing a first main plane St and a second main plane Sb and at least one retaining member Pr1, Pr2, Pr4 having a slit member S comprised of at least one slit formed in a top surface Sru at a first predetermined height t2 from the second main plane Sb for accepting a part of perimeter of the water absorbent sheet Sa1 being inserted therein.提供一種吸水片材保持墊,其可以容易且確實之方式將吸水片材加以保持。將具有第1多角形輪廓之吸水片材Sa1加以保持之吸水片材保持墊M1、M2、M3、M4,係具備有:墊部Pm1、Pm2、Pm3、Pm4,其具有由相互對向之第1主面St及第2主面Sb所界定之2多角形輪廓;及至少一個保持部Pr1、Pr2、Pr4,其於下表面Sru形成有自上述第2主面Sb且形成於第1既定高度t2之狹縫部S,而該狹縫部S係具有供上述吸水片材Sa1之周邊部之一部分進行插入之至少一條狹縫。Esa‧‧‧吸水片材之端部Gr1‧‧‧槽部Lls‧‧‧吸水片材之長邊Lpr‧‧‧片材緣寬度Lss‧‧‧吸水片材之短邊M1‧‧‧吸水片材保持墊Pm1‧‧‧墊部Pr1‧‧‧保持部S‧‧‧狹縫部Sa1‧‧‧吸水片材Sb‧‧‧設置面Spa‧‧‧吸水區域Spr‧‧‧片材緣部Spc‧‧‧角隅部St‧‧‧載置面t1、t2、t3‧‧‧距離
