A battery unit and a battery module including a plurality of battery units. A battery unit includes: a case accommodating an electrode assembly and having an opening; a cap plate covering the opening and having a terminal insertion portion penetrating the cap plate; a terminal member extending into the case through the terminal insertion portion to electrically expose the electrode assembly outside of the case; and a fixing member in the terminal insertion portion and fixing the terminal member to the cap plate, the fixing member being formed by an insert injection molding method in which a plastic resin is injected in the terminal insertion portion in a state in which the terminal member is inserted in the terminal insertion portion, the fixing member including a recessed portion that is recessed from an upper surface of the fixing member.