Abstract: An amino acid-N,N-diacetic acid (AADA) or its salt with an equivalent or less of an alkali metal is produced by reducing, through electrodialysis, alkali metal ions from an aqueous solution of the alkali metal salt of an AADA. By this configuration, an AADA salt can be produced in a much higher yield than conventional equivalents without requiring a regeneration operation of a resin as in the use of an ion exchange resin or without requiring crystallization-separation of crystals of the AADA salt as in the addition of an organic solvent. A salt of an amino acid-N,N-diacetic acid is also produced by reacting an AADA with any of metal oxides, metal hydroxides, metal carbonates, metal hydrogencarbonates, ammonium hydroxide, ammonium carbonate, ammonium hydrogencarbonate or organic amine compounds. By this configuration, a metal salt, ammonium salt or organic amine salt of an AADA can be produced with efficiency without the formation of by-products.