Abstract: An acetic acid- and/or acetate salt-free iron metabolism-improving agent that contains citric acid and/or a citrate salt as electrolytes and also contains another/other electrolyte/electrolytes and glucose solely or in combination is provided. The iron metabolism-improving agent can be formulated into a dialysate and/or a substitution fluid. A method for improving internal iron metabolism and a blood purification method including hemodialysis and hemodiafiltration in a chronic renal failure patient employing the dialysate and/or the substitution fluid are further provided.