The invention provides a novel adrenomedullin derivative sustainable for along periodwhich is capable of substantially suppressing unwanted side effects whilemaintainingpharmacological effects of adrenomedullin. In an exemplary embodiment, theinventionrelates to a compound represented by formula (I): A-CH2-B (I) [wherein A is amodifyinggroup comprising one or more polyethylene glycol groups, and B is a peptidemoiety derivedfrom adrenomedullin or a modified form thereof with adrenomedullin activity,wherein thepeptide moiety B is linked to the other moieties through a covalent bond ofthe nitrogen atomof the N-terminal .alpha.-amino group of the peptide moiety B to the carbonatom of the methylenegoup] or a salt thereof, or a hydrate thereof.
