NOVELTY - Metals are recovered (S101) from positive electrode material of lithium ion battery, and positive electrode material is dissolved in acidic solution, and lithium ion and transition metal ion are produced in acidic solution. Acidic solution is poured and liquid containing lithium ion and transition metal ion is recovered on both sides of anion permeable film, and lithium ion is dialyzed (S108,S109) from acidic solution. The lithium ion is recovered (S110,S111) from recovering liquid and addition process is performed. Thus, recovery of metal is enabled.    USE - Recovery of metal. Uses include but are not limited to electric tool, electric-power-assisted bicycle, electric vehicle, mobile telephone, portable music player, spacer, casing, safety valve, separator, collector, etc.    ADVANTAGE - The method efficiently recovers metal with improved permeability, by simple method.    DETAILED DESCRIPTION - Metals are recovered from the positive electrode material of lithium ion battery containing lithium and a transition metal element, and positive electrode material is dissolved in an acidic solution, and lithium ion and a transition metal ion are produced in the acidic solution. The acidic solution is poured and liquid containing the lithium ion and transition metal ion is recovered on both sides of an anion permeable film, and lithium ion is dialyzed from the acidic solution to the recovery solution. The lithium ion is recovered from the recovering liquid containing dialyzed lithium ion and addition process is performed by adding primary additive to the hydrophilic acidic solution inside the dialysis membrane. Thus, recovery of metal is enabled. An INDEPENDENT CLAIM is included for dialysis promoter.    DESCRIPTION OF DRAWING(S) - The drawing shows the flowchart of recovery of metal. (Drawing includes non-English language text)    Recovery process (S101)    Separation process (S102)    Dialysis (S106)    Dialysis process (S108,S109)    Separate-and-recovery process (S110,S111)