1. A cyclic compound of the formula (I) or a pharmacologically acceptable salt thereof, ##STR00001## wherein X is .dbd.CH-- or .dbd.N--, Y is --NH--, --NR.sup.4--, --S--, --O--, --CH.dbd.N--, --N.dbd.CH--, --N.dbd.N--, --CH.dbd.CH--, etc., R.sup.1 is a lower alkoxy group, an amino group, a heterocyclic ring containing N atom(s), or a hydroxy group substituted by a heterocyclic ring containing N atom(s) (each of which is optionally substituted), R.sup.2 is a lower alkylamino group which is optionally substituted by an aryl group, a lower alkoxy group which is optionally substituted by an aryl group, a lower alkoxy group substituted by an aromatic heterocyclic ring containing N atom(s), R.sup.3 is an aryl group, a heterocyclic ring containing N atom(s), a lower alkyl group, a lower alkoxy group, a cyclo lower alkoxy group, a hydroxy group substituted by a heterocyclic ring containing N atom(s), or an amino group (each of which is optionally substituted), and R.sup.3 and a substituent in Y may be combined to form a lactone ring. The compound of the present invention has excellent selective PDE V inhibitory activity and therefore, is useful as a therapeutic or prophylactic drug for treating various diseases due to functional disorders on cGMP-signaling.