Provided are a system for and a method of processing a waste lithium-ion battery, the system and the method making it possible to improve the recovery rate of lithium. One example of the system for processing a waste lithium-ion battery according to the present invention includes: a first aqueous solution generator (1) that includes a first elution tank (1a) storing water, and that immerses an active material taken out from the waste lithium-ion battery in the water in the first elution tank (1a) and subjects the active material to carbon dioxide bubbling in the first elution tank (1a) to generate an aqueous solution of pH 5.5 to 8.5, in which lithium contained in the active material is eluted; a first solid-liquid separator (2) that removes a solid component from the aqueous solution generated by the first aqueous solution generator (1); a first crystallizer (3) that causes lithium carbonate to be deposited from the aqueous solution, from which the solid component has been removed by the first solid-liquid separator (2); and a second solid-liquid separator (4) that performs solid-liquid separation on slurry containing the lithium carbonate deposited in the first crystallizer (3) to take out the lithium carbonate.