The invention provides pyridone derivatives represented by a general formula (I) ##STR00001## [in the formula, R.sub.1 and R.sub.2 may be same or different and stands for H, etc., or R.sub.1 and R.sub.2 may form an aliphatic nitrogen-containing heterocyclic group together with the N to which they bind; X.sub.1-X.sub.3 may be same or different and stand for methine or N, provided not all of them simultaneously stand for nitrogen; X.sub.4-X.sub.7 may be same or different and stand for methine or N, provided that three or more of them do not simultaneously stand for N; Y.sub.1 and Y.sub.3 may be same or different and stand for single bond, --O--, --NR--, --S--, etc; Y.sub.2 stands for lower lkylene, etc.; R stands for H, etc., L stands for methylene; Z.sub.1 and Z.sub.2 may be same or different and stand for single bond or lower alkylene; or R.sub.1, L and Z.sub.2 may form an aliphatic nitrogen-containing heterocyclic group with the N to which R.sub.1 binds; and Ar stands for aromatic carbocyclic group, etc.].