A 1,2-dihydro-2-oxoquinoline derivative represented by the formula:
wherein Ar is a pyridyl group or a group represented by the formula:
(wherein X 3 and X 4 are the same or different, and are each a hydrogen atom, a halogen atom, a C 1-5 alkyl group, a C 1-5 alkoxy group, a hydroxyl group or a trifluoromethyl group), Y is a nitrogen atom, CH or C(OH), R 1 and R 2 are the same or different, and are each a hydrogen atom, a C 1-10 alkyl group, a C 3-15 alkoxyalkyl group or a C 3-15 alkylaminoalkyl group, or R 1 and R 2 taken together with the nitrogen atom to which they are attached form a cyclic amino group, X 1 and X 2 are the same or different, and are each a hydrogen atom, a C 1-5 alkyl group, a C 1-5 alkoxy group or a halogen atom, or X 1 and X 2 taken together form an alkylenedioxy group, and n is an integer of 1 to 3; or a pharmaceutically acceptable salt thereof.