The present invention provides a prophylactic or therapeutic agent for a kidney disease, comprising Apoptosis Inhibitor of Macrophage (AIM) or a partial peptide thereof, or a nucleic acid comprising a base sequence encoding the same, or a screening method for a prophylactic or therapeutic agent for a kidney disease, comprising using an animal obtained by subjecting a non-human mammal deficient in AIM expression to unilateral ureteral obstruction or transient kidney ischemia/reperfusion and the like.