The present disclosure relates to an ammonia synthesis apparatus, and more particularly, to an electrochemical ammonia synthesis apparatus using an aqueous solution or a molten liquid of an alkali metal as an electrolyte. According to one or more embodiments, when an aqueous solution or a molten liquid of an alkali metal is used as an electrolyte in an ammonia synthesis apparatus, compositions, sizes, and shapes of an electrode and an electrolyte may be easily controlled, and thus a yield of ammonia synthesis may improve.