A method for improving glomerular filtration rate includes administering to a subject in need thereof an agent containing a culture of a bacterium belonging to the genus Bacillus. A method for ameliorating renal failure includes administering to a subject in need thereof an agent with a serum creatinine-lowering effect containing as an active ingredient a culture of a genus Bacillus bacterium. A method for improving glomerular filtration rate or ameliorating renal failure includes administering to a subject in need thereof an agent containing spores of a bacterium belonging to the genus Bacillus.
