An object of the present invention is to provide a pharmaceutical agent useful for treating and preventing neurological disease, having satisfactory solubility and oxidative stress-mediated cell death suppressive activity as well as capable of exhibiting excellent blood-brain barrier permeability. The present invention is directed to an acylaminoimidazole derivative represented by general formula (I) or a salt thereof, and a pharmaceutical and a therapeutic or preventive agent for neurological disease containing the same, as an active ingredient.