A starting solution material in the form of waste produced in the course of separation and recovery of sucrose from sugar beet extract or sugar beet molasses with a 2-component separation simulated moving bed chromatographic separator (using a strongly acidic cation exchange resin in a salt form as chromatographic packing) or its concentrate is used to separate therefrom a crude betaine fraction with a 2-component separation simulated moving bed chromatographic separator using as chromatographic packing a strongly acidic cation exchange resin in an ionic form equilibrated with that of the strating solution material. The crude betaine fraction or its concentrate is used to separate therefrom a betaine fraction with a 2-component separation simulated moving bed chromatographic separator using as chromatographic packing a strongly acidic cation exchange resin having at least 10 % (based on the ion exchange capacity) of the ionic form thereof changed to the Ca form. The betaine fraction may be concentrated and subjected to crystallization, whereby high-purity betaine can be obtained.