To provide a method capable of isolating easily Ga ions at high concentration in a short time from a liquid mixture containing one or more Ga ions selected from Ga isotopes and ions of an element in the fourth period other than Ga, to provide an apparatus used in the method, and to provide a method of producing a Ga label compound and an apparatus for producing the Ga label compound.

The method of isolating Ga ions from a liquid mixture containing the Ga ions and the ions of the element in the fourth period other than Ga includes: contacting the liquid mixture with an anion exchange resin; allowing the Ga ions and the ions of the element in the fourth period other than Ga to be adsorbed in the anion exchange resin; cleaning the adsorbed anion exchange resin with an alcohol; eluting the Ga ions by cleaning with water or a dilute acidic aqueous solution to acquire an aqueous solution containing the Ga ions.