PROBLEM TO BE SOLVED: To provide siRNA effective for treating fibrosis, and to provide a pharmaceutical agent using the same.SOLUTION: The present invention provides a siRNA targeting 17 to 23 consecutive bases selected from the 1285th to the 1318th bases, the 1398th to the 1418th bases, the 1434th to the 1463rd bases, the 1548th to the 1579th bases, the 1608th to the 1628th bases, the 1700th to the 1726th bases, the 1778th to the 1798th bases, the 1806th to the 1826th bases, and the 1887th to the 1907th bases, in a specific base sequence consisting of 2346 bases, the siRNA having a full-length of 30 nucleotides or less. Preferably, consecutive 1-10 nucleotides except an overhang nucleotide from the 3'-terminal side of the siRNA sense strand is converted into DNA.SELECTED DRAWING: Figure 1【課題】線維症を治療するために有効なｓｉＲＮＡ及びこれを用いた医薬の提供。【解決手段】２３４６塩基よりなる特定の塩基配列において、塩基番号１２８５～１３１８番の塩基、１３９８～１４１８番の塩基、１４３４～１４６３番の塩基、１５４８～１５７９番の塩基、１６０８～１６２８番の塩基、１７００～１７２６番の塩基、１７７８～１７９８番の塩基、１８０６～１８２６番の塩基及び１８８７～１９０７番の塩基より選ばれる連続する１７～２３塩基を標的配列とし、全長が３０ヌクレオチド以下であるｓｉＲＮＡ。ｓｉＲＮＡのセンス鎖の３’末端側からのオーバーハングヌクレオチドを除いた連続する１～１０ヌクレオチドがＤＮＡに変換されることが好ましいｓｉＲＮＡ【選択図】図１
