A snake venom of the Madaraumi snake having the amino acid sequence shown in SEQ ID NO: 2 and capable of achieving selective modification by covalent bond between the carboxyl group of mPEG2000 and the free amino group of the N-terminal aspartic acid of the peptide chain of Hydrostatin-SN10. Derivatives of selective TNFR1 antagonist peptide Hydrostatin-SN10 are provided. The selective TNFR1 antagonist peptides Hydrostatin-SN10 and PEG-SN10 are applicable for the treatment of inflammatory bowel disease. [Selection diagram] None配列番号２に示されるアミノ酸配列を有し、ｍＰＥＧ２０００のカルボキシル基とＨｙｄｒｏｓｔａｔｉｎ－ＳＮ１０のペプチド鎖のＮ端アスパラギン酸の遊離アミノ基との共有結合により選択的修飾を実現できる、マダラウミヘビのヘビ毒に由来する選択性ＴＮＦＲ１拮抗ペプチドＨｙｄｒｏｓｔａｔｉｎ－ＳＮ１０が提供される。選択性ＴＮＦＲ１拮抗ペプチドＨｙｄｒｏｓｔａｔｉｎ－ＳＮ１０及びＰＥＧ－ＳＮ１０は、炎症性腸疾患の治療に適用できる。【選択図】なし
