PROBLEM TO BE SOLVED: To provide a window sill which can be firmly fixed to a lower frame of a window with a minimum processing of existing parts, allowing a lower space as well as an upper space to be effectively utilized after fixation.SOLUTION: A window sill 10 to be fixed to a front part 3 of a lower frame 2 of an existing window 1 which is located at a position higher at least than the floor comprises a tabular base body 20 horizontally projecting from the front part 3 toward the indoor side and a fixing component 30 which fixes the base body 20 and the lower frame 2. The fixing component 30 is provided with a lower frame fixing part 31 which has a height and a width smaller than the thickness and the width of the lower frame 2, respectively, and is fixed to the front part 3 of the lower frame 2, and a horizontal fixing part 32 projecting in horizontal direction from the lower frame fixing part 31 toward the indoor side. The base body 20 in a state installed to the lower frame 2 covers at least the upper face part of the lower frame fixing part 31.COPYRIGHT: (C)2012,JPO&INPIT【課題】窓の下枠を利用して既存側への加工を最小限にとどめ、且つ、強固に取り付けることができ、また、取付け後は上部空間のみならず下方空間も有効に利用することができるようにする。【解決手段】少なくとも床より高いところにある既存の窓1の下枠2の見付け部3に取り付けられる窓台10であって、見付け部3から屋内側に向けて水平に突出する板状の台本体20と、該台本体20と下枠2とを固定する取付け部材30とからなり、取付け部材30は、下枠2の厚さ及び幅よりも小さい高さと幅を有して当該下枠2の見付け部3に固定される下枠取付き部31と、該下枠取付き部31から屋内に向けて水平方向に突出する水平取付け部32と、を備え、台本体20は、下枠2に設置された状態で下枠取付き部31の少なくとも上面部が覆われた状態とする。【選択図】図2