Recent clinical studies have demonstrated the protective effect of xanthine oxidase (XO) inhibitors against chronic kidney diseases, although the underlying molecular mechanisms remain unclear. However, to date, neither clinical nor basic research has been carried out to elucidate the efficacy of XO inhibitor administration for IgA nephropathy. We thus investigated whether febuxostat, an XO inhibitor, exerts a protective effect against the development of IgA nephropathy, using gddY mice as an IgA nephropathy rodent model. Eight-week-old gddY mice were provided drinking water with (15 μg/mL) or without febuxostat for nine weeks and then subjected to experimentation. Elevated serum creatinine and degrees of glomerular sclerosis and fibrosis, judged by microscopic observations, were significantly milder in the febuxostat-treated than in the untreated gddY mice, while body weights and serum IgA concentrations did not differ between the two groups. In addition, elevated mRNA levels of inflammatory cytokines such as TNFα, MCP-1, IL-1β, and IL-6, collagen isoforms and chemokines in the gddY mouse kidneys were clearly normalized by the administration of febuxostat. These data suggest a protective effect of XO inhibitors against the development of IgA nephropathy, possibly via suppression of inflammation and its resultant fibrotic changes, without affecting the serum IgA concentration.