The present invention addresses the problem of providing an agent for preventing or improving renal dysfunction, having an excellent inhibitory action on the advance of renal dysfunction, inhibitory action on renal fibrosis, inhibitory action on the development of renal failure, and inhibitory action on nephritis. The advance of renal dysfunction can be impeded, renal fibrosis can be inhibited, the development of renal failure can be inhibited, and nephritis can be inhibited when an agent to prevent or improve renal dysfunction containing lubiprostone or a pharmaceutically acceptable salt thereof as an active ingredient is administered orally or the like. Therefore, nephritides such as acute glomerulonephritis, minimal change nephritis, chronic glomerulonephritis, renal sclerosis, membrane proliferative nephritis, mesangial proliferative glomerulonephritis, membrane proliferative glomerulonephritis, crescentic nephritis, rapidly progressive glomerulonephritis, membranous glomerulonephritis, tubulointerstitial nephritis, acute pyelonephritis, chronic pyelonephritis, endocapillary proliferative nephritis, lupus nephritis, and the like； renal failures such as acute renal failure, chronic renal failure, and the like； as well as renal dysfunctions such as amyloid kidney disease, membranous nephropathy, focal glomerulosclerosis, IgA nephropathy, acute tubular necrosis, nephrotic syndrome, diabetic nephropathy, gouty kidney, renal edema, renal tumors, renal ischemic disorders, renal ischemia-reperfusion injury, and the like can be prevented or improved.La présente invention aborde le problème de fourniture d'un agent servant à prévenir ou améliorer un dysfonctionnement rénal, possédant une excellente action inhibitrice sur la progression d'un dysfonctionnement rénal, une action inhibitrice sur la fibrose rénale, une action inhibitrice sur le développement de l'insuffisance rénale, et une action inhibitrice sur la néphrite. L'avancement d'un dysfonctionnement rénal peut êtr
