A problem to be solved by the present invention is to provide a peptide compound for producing a drug delivery carrier capable of releasing a target substance in a weakly acidic pH environment. The present invention provides a peptide compound comprising a hydrophilic amino acid block and a hydrophobic amino acid block [1] the peptide compound containing 24 to 36 amino acids in total [2] the hydrophilic amino acid block containing 4 to 10 amino acids in total and having an average hydropathy index of −3.0 to −1.0 and [3] the hydrophobic amino acid block containing 20 to 32 amino acids in total, containing one or more His residues, and having an average hydropathy index of 1.0 to 2.5.
