Method for producing lithium-containing solution

A method for producing a lithium-containing solution, comprising

• an adsorption step of bringing a lithium adsorbent obtained from lithium manganese oxide into contact with a low concentration lithium-containing solution to obtain post-adsorption lithium manganese oxide;
• an eluting step of bringing the post-adsorption lithium manganese oxide into contact with an acid-containing solution to obtain an eluted solution;
• and
• a manganese oxidation step of oxidating manganese by adding an oxidant and a pH adjuster to the eluted solution to obtain a lithium-containing solution with a suppressed manganese concentration, wherein
• the adsorption step, the eluting step, and the manganese oxidation step are performed in this order,
• in the eluting step, the eluted solution is separated into a high concentration lithium-eluted solution containing lithium at a high concentration and a low concentration lithium-eluted solution having a lithium concentration lower than the lithium concentration of the high concentration lithium-eluted solution,
• the acid-containing solution in the eluting step includes a solution prepared by adding acid to the low concentration lithium-eluted solution,
• the eluted solution used in the manganese oxidation step includes the high concentration lithium-eluted solution, and
• the high concentration lithium-eluted solution is, among the eluted solution obtained through the eluting step, the eluted solution extracted by a predetermined volume based on a start of obtaining the eluted solution.