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 X3 and X4 are the same or different, and are each a hydrogen atom, a halogen atom, a C1-5 alkyl group, a C1-5 alkoxy group, a hydroxyl group or a trifluoromethyl group), Y is a nitrogen atom, CH or C(OH), R1 and R2 are the same or different, and are each a hydrogen atom, a C1-10 alkyl group, a C3-15 alkoxyalkyl group or a C3-15 alkylaminoalkyl group, or R1 and R2 taken together with the nitrogen atom to which they are attached form a cyclic amino group, X1 and X2 are the same or different, and are each a hydrogen atom, a C1-5 alkyl group, a C1-5 alkoxy group or a halogen atom, or X1 and X2 taken together form an alkylenedioxy group, and n is an integer of 1 to 3; or a pharmaceutically acceptable salt thereof.