Provided is a metal-air battery and a method of using the same that make it possible to obtain a high output while also promoting the discharge of product associated with power generation and achieve stable output over time. A metal-air battery according to the present invention comprises a metal-air battery unit provided with a plurality of metal-air battery cells in parallel, each metal-air battery cell being configured to include a metal electrode, air electrodes disposed facing each other on either side of the metal electrode, and a housing that supports the metal electrode and the air electrodes, wherein the air electrodes are exposed on an outer face on either side of the housing, a liquid chamber is formed in each housing, and in the metal-air battery unit, an air chamber that is open on top is formed between the facing air electrodes between each of the metal-air battery cells, and in each metal-air battery cell, a through-hole that communicates to the liquid chamber and is supplies an electrolytic solution to the liquid chamber and can also release a product produced by a reaction between the metal electrode and the air electrodes to the outside of the metal-air battery unit is formed.