The present invention provides a novel peptide having accumulation specific to biliary tract cancers. The present invention is the following peptide (a) or (b). (A) a peptide consisting of an amino acid sequence comprising the sequence represented by SEQ ID NO: 1, (b) an amino acid sequence comprising a sequence having at least 60% identity to the sequence represented by SEQ ID NO: 1, Peptide having accumulation specific to cancer本発明は、胆道癌に特異的な集積性を有する新規ペプチドを提供する。本発明は、以下の(a)又は(b)のペプチドである。(a)配列番号1で表される配列を含むアミノ酸配列からなるペプチド、(b)配列番号1で表される配列と同一性が60%以上である配列を含むアミノ酸配列からなり、且つ、胆道癌に特異的な集積性を有するペプチド