This peptide is composed of an amino acid sequence represented by general formula (I), and has a high degree of accumulation in cancer cells or cancer tissue in a digestive system. (In general formula (I), X11 is a peptide residue composed of an amino acid sequence of (a) or (b) below: (a) an amino acid sequence represented by any of SEQ ID NOs: 1 to 3, (b) an amino acid sequence including a sequence in which one or two amino acids have been deleted, substituted or added in an amino acid sequence represented by any of SEQ m NOs: 1 to 3; Y11 is a peptide linker composed of an amino acid residue of at least 1 but not more than 10 amino acids, wherein each amino acid residue is independently a glycine residue, a proline residue, a serine residue a cysteine residue or a lysine residue; X12 is either a peptide residue composed of an amino acid sequence of (a) or (b) above, or a retro-inverso peptide residue thereof; and n11 represents an integer of at least 1 but not more than 9.) [Formula 1] X11—(Y11—X12)n11  (I)