The invention provides pyridone derivatives represented by a general formula (I) [in the formula, R1 and R2 may be same or different and stands for H, etc., or R1 and R2 may form an aliphatic nitrogen-containing heterocyclic group together with the N to which they bind; X1-X3 may be same or different and stand for methine or N, provided not all of them simultaneously stand for nitrogen; X4-X7 may be same or different and stand for methine or N, provided that three or more of them do not simultaneously stand for N; Y1 and Y3 may be same or different and stand for single bond, —O—, —NR—, —S—, etc; Y2 stands for lower alkylene, etc.; R stands for H, etc., L stands for methylene; Z1 and Z2 may be same or different and stand for single bond or lower alkylene; or R1, L and Z2 may form an aliphatic nitrogen-containing heterocyclic group with the N to which R1 binds; and Ar stands for aromatic carbocyclic group, etc.].