An ion removal system includes: an electrolysis device configured to generate alkaline water and acid water by electrolysis; a hard water flow path to supply the electrolysis device with hard water; a first flow path and a second flow path through which the alkaline water and the acid water generated by the electrolysis device can alternately flow; a fine bubble generation device configured to generate and supply fine bubbles to the hard water flow path, the first flow path, or the second flow path so as to adsorb and remove metal ions in water by the fine bubbles generated; and a controller, wherein the controller controls the electrolysis device to perform a first mode in which the alkaline water is allowed to flow through the first flow path and the acid water is allowed to flow through the second flow path and a second mode in which the acid water is allowed to flow through the first flow path and the alkaline water is allowed to flow through the second flow path.