· Separation method for extraction of the rare earth element

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PROBLEM TO BE SOLVED : To provide a method for satisfactorily extracting and separating rare earth elements, particularly, adjacent rare earth elements such as Nd/Pr.SOLUTION : An organic phase comprising diglycol amide acid expressed by general formula (1) (Rand Rdenote the same or different alkyl groups, and at least either denotes a ≥6C linear or branched alkyl group) as an extractant and a water phase composed of an aqueous solution comprising two or more of rare earth elements are contacted under an acid condition at the pH of ≤3, the rare earth element(s) to be extracted in the rare earth elements is extracted into the organic phase, thereafter, the organic phase is back-extracted in an acid aqueous solution so as to recover the rare earth element(s) extracted into the organic phase, further, the rare earth element(s) not extracted into the organic phase and remaining in the water phase is recovered, the organic phase after the separation of the rare earth element(s) is cleaned with an acid aqueous solution with the pH of 3 to 7, and the cleaned organic phase is reused for extraction treatment.