The present invention provides a peptide comprising the amino acid sequence of any of the formulas (I)-(III) below: (I) an amino acid sequence of (X1)[D]P[D](X2)[D] wherein X1 is W or F, X2 is S or T, and each amino acid symbol immediately followed by symbol [D] is a D form of the amino acid, (II) an amino acid sequence of P[D]T[D](X)n F[D] wherein (X)n is any amino acid in the number of n selected independently of each other, n is an integer of 0-4, and the symbol [D] is as defined above, (III) an amino acid sequence that is a Retro-inverso of the amino acid sequence of any of the aforementioned (I) and the aforementioned (II); and a conjugate containing the peptide and a functional part.