PURPOSE: To obtain ion exchange resin particles having the purity exceeding the purity of the resin particles obtd. thus far by passing a second liquid which receives ions from refined water through blocks for concentrating and impressing voltage between an anode and a cathode to recover the cleaned resin particles.

CONSTITUTION: The apparatus has the cathode block at its first end, the anode block on its opposite side and a plurality of sets of blocks 40 for decreasing anions and blocks 42 for decreasing cations existing alternately with the blocks 52 for concentrating ions. The respective blocks 40 for decreasing anions and blocks 42 for decreasing cations are parted by bifunctional boundaries 46. While the refined water is passed through the blocks 40 for decreasing anions and the blocks 42 for decreasing cations, the second liquid which receives the ions from the refined water is passed through the blocks 52 for concentrating ions. The cleaned resin particles are recovered by impressing voltage between the anode 54 of the anode block and the cathode 50 of the cathode block.