A TGF-β gene expression inhibitor containing a pyrrole-immidazole polyamide comprising an N-methylpyrrole unit (hereinafter also referred to as Py), an N-methylimidazole unit (hereinafter also referred to as Im) and a γ-aminobutyric acid unit which can be folded into an U-shaped conformation at the above-described γ-aminobutyric acid unit site in a minor groove of a double-stranded region (hereinafter referred to as the target region) containing a part or the whole of the following base sequence (SEQ ID NO: 2) corresponding to −450 to −310 of human transforming growth factor β1 (hereinafter also referred to as h TGF-β1) promoter and a strand complementary thereto and in which a Py/Im pair, an Im/Py pair and a PY/Py pair correspond respectively to a C-G base pair, a G-C base pair and an A-T base pair and a T-A base pair.