A decrease in power output an increase in inner pressure during discharge are prevented even when deposition of the reaction product increases with the discharge and the volume of the electrolytic solution increases with progress of the reaction. An air battery system of the present invention includes: an air battery 20 and a reservoir tank 50 to reserve electrolytic solution to be supplied to the air battery 20, wherein a reaction product sump 10 to store reaction product produced in the air battery 20 is provided between the air battery 20 and the reservoir tank 50.
