A method of producing lithium hydroxide using a variety of aqueous solutions as a source liquid. The method includes: providing a lithium ion extraction liquid, including a first mixing of an aqueous solution containing lithium and at least one kind of an element other than lithium and a base in a reaction tank, with a pH regulated to 6 or more and 10 or less, a second mixing of the aqueous solution and the base, with a pH regulated to 12 or more, and removal of a hydroxide of the element other than lithium formed through the first and second mixing; recovering only lithium ion from the lithium ion extraction liquid to a recovery liquid with an electrochemical device including a Li-selectively permeable membrane; and performing the regulation of pH by returning the lithium ion extraction liquid after recovering lithium ion with the electrochemical device to the reaction tank.