the present invention provides a quinolone compound that inhibits the chronic progression of parkinson &# 39 ; s disease or protects dopamine neurons from disease etiology , thereby suppressing the progression of neurological dysfunction , so as to prolong the period of time until l - dopa is administered while also improving neuronal function ; the quinolone compound of the invention is represented by formula : wherein : r 1 represents hydrogen or the like ; r 2 represents hydrogen or the like ; r 3 represents substituted or unsubstituted phenyl or the like ; r 4 represents halogen or the like ; r 5 represents hydrogen or the like ; r 6 represents hydrogen or the like ; and r 7 represents hydrogen or the like .