A pharmaceutical composition for transnasal administration containing a hydrophilic bioactive substance and any one of the following peptides (a) to (c) enables transnasal administration of the hydrophilic bioactive substance which is poor in transmucosal absorption and could be conventionally administered only through injection, and is useful as a pharmaceutical composition capable of improving pain and inconvenience of patients involved in administration via injection. (a) a peptide containing an amino acid sequence represented by SEQ ID NO: 1； (b) a peptide containing an amino acid sequence with deletion, substitution or addition of one or several amino acids in the amino acid sequence represented by SEQ ID NO: 1 and having nasal mucosa permeability； and (c) a peptide containing an amino acid sequence represented by a reverse sequence to the sequences in (a) or (b) and having nasal mucosa permeability.
