Provided is siRNA effective for the treatment of fibrosis and a pharmaceutical containing the siRNA. An siRNA having a full length of 30 or fewer nucleotides and targeting a sequence consisting of 17 to 23 consecutive bases selected from the group consisting of bases at positions 1285 to 1318, bases at positions 1398 to 1418, bases at positions 1434 to 1463, bases at positions 1548 to 1579, bases at positions 1608 to 1628, bases at positions 1700 to 1726, bases at positions 1778 to 1798, bases at positions 1806 to 1826, and bases at positions 1887 to 1907 of SEQ ID NO: 1.
