1. A cyclic compound of the formula (I) or a pharmacologically acceptable salt thereof, wherein X is =CH- or =N-, Y is -NH-, -NR<4>-, -S-, -O-, -CH=N-, -N=CH-, -N=N-, -CH=CH-, etc., R<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<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<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<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.