NOVELTY - Metal-air battery system (20) comprises: metal-air battery including case (1) and charge/discharge member arranged in case and having cathode (4), anode and electrolyte; carbon dioxide absorbing member (6) having carbon dioxide selective absorber (5) selectively absorbing carbon dioxide over oxygen; outside air supplying member supplying outside air to carbon dioxide absorbing member; purified air supplying member supplying purified air to cathode; and recycling mechanism recycling carbon dioxide selective absorber.    USE - Used as metal-air battery system.    ADVANTAGE - The metal-air battery system: can stably utilize air from which carbon dioxide has been removed for discharge of a metal-air battery; and utilizes carbon dioxide selective absorber that allows oxygen permeation, suppresses carbon dioxide permeation and sufficiently adsorbs carbon dioxide.    DETAILED DESCRIPTION - Metal-air battery system (20) comprises: a metal-air battery including a case (1) and a charge/discharge member arranged in the case and having a cathode (4), an anode and an electrolyte; a carbon dioxide absorbing member (6) having a carbon dioxide selective absorber (5) selectively absorbing carbon dioxide over oxygen; an outside air supplying member supplying outside air to the carbon dioxide absorbing member; a purified air supplying member supplying purified air to the cathode, where the purified air has undergone absorptive carbon dioxide removal by the carbon dioxide selective absorber; and a recycling mechanism recycling the carbon dioxide selective absorber. An INDEPENDENT CLAIM is also included for operating a metal-air battery system, comprising: a discharging step of discharging electricity by supplying air to the cathode, where the air has undergone absorptive carbon dioxide removal by the carbon dioxide selective absorber; and a recycling step of recycling the carbon dioxide selective absorber.    DESCRIPTION OF DRAWING(S) - The figure shows a schematic view of part of the metal-air battery system.    Case (1)    Cathode (4)    Carbon dioxide selective absorber (5)    Carbon dioxide absorbing member (6)    Metal-air battery system (20)