The present invention provides a compound having melanocortin receptor agonist activity or antagonist activity, which is a novel biaryl compound represented by the formula (I): ##STR00001## wherein ring A and ring B are optionally further substituted 6-membered aromatic rings; X is --CONR.sup.4--, --SO.sub.2NR.sup.4--, --CH.sub.2NR.sup.4-- (R.sup.4 is a hydrogen atom, an optionally substituted hydrocarbon group, etc.), etc.; Y is a spacer having 1 to 12 atoms, etc.; Z is --CONR.sup.6--, --CO-- (R.sup.6 is a hydrogen atom, an optionally substituted hydrocarbon group or an optionally substituted heterocyclic group), etc.; R.sup.1 is an optionally substituted amino group, etc.; R.sup.2 is an optionally substituted hydrocarbon group, etc.; R.sup.3 is an optionally substituted hydrocarbon group, etc.; and R.sup.5 is an optionally substituted hydrocarbon group, etc.; or a salt thereof.