The present invention provides a peptide fragment or a series of peptide fragments having a cell death-inhibitory activity, having the amino acid sequence consisting of 103 amino acid residues at the C-terminal of selenoprotein P, or having said amino acid sequence with one or several amino acid residues therein being deleted, substituted or added, or having a partial sequence of either of the above amino acid sequences, a medicament for treatment comprising said peptide fragment or a series of peptide fragments, an antibody to said peptide fragment or a series of peptide fragments, and a method for screening a cell death-inhibitory activity using said peptide fragment or a series of peptide fragments. The preferable peptide fragment or a series of peptide fragments of the present invention has the amino acid sequences shown in SEQ ID NO: 1 and/or SEQ ID NO: 2 or has a partial sequence thereof.