Provided is a renal function improving agent that is usable for preventing or suppressing a worsening in renal function without largely changing previous eating habits. A renal function improving agent to be taken by a person who shows an abnormal value of at least one factor selected from blood urea nitrogen concentration, blood creatinine concentration and daily urinary albumin excretion, said renal function improving agent comprising, per 100 kcal of energy, 0.5-4 g of protein, 10-40 mg of phosphorus, 10-70 mg of sodium and 5-50 mg of potassium.
