(EN) This ion removal system is provided with: an electrolysis device which generates alkaline water and acidic water through electrolysis; a hard water flow passage which is connected to the electrolysis device and supplies hard water to the electrolysis device; a batch processing tank which is provided in the middle of the hard water flow passage and contains the hard water; a return flow passage which is connected to the batch processing tank so as to return, to the batch processing tank, the alkaline water and the acidic water generated by the electrolysis device; a microbubble generator which generates microbubbles in a circulation flow passage including the batch processing tank, the electrolysis device, and the return flow passage, and which adsorbs and removes metal ions in water by means of the generated microbubbles.