A developer container comprising: a container body that stores a developer and includes a filling port for the developer, wherein a cap member is attached to the filling port in order to seal the filling port; and a container terminal that is attachable to and detachable from the container body and is electrically connectable to a terminal of an image forming apparatus, wherein the developer container is attachable to and detachable from the image forming apparatus and, when attached to the image forming apparatus, is electrically connected to the terminal of the image forming apparatus, the container body is provided with an identifier configured to engage with the container terminal, characterized in that the identifier is configured to change its own form that can be identified from an outside, by an external force that is applied to detach the container terminal from the container body, wherein the container body is provided with a flow preparation part that separates an inside and outside of the container body before changing the form of the identifier and allows the air to flow between the inside and outside of the container body after changing the form of the identifier, wherein the container body includes an airflow hole different from the filling port that allows the air to flow between an inside and an outside of the container body, and the airflow hole is formed by separating the identifier that engages with the container terminal, from the container body with the external force that is applied to detach the container terminal from the container body, wherein the identifier is formed of a protrusion that protrudes from the container body and is to be broken by the external force. a container body that stores a developer and includes a filling port for the developer, wherein a cap member is attached to the filling port in order to seal the filling port; and a container terminal that is attachable to and detachable from the container body and is electrically connectable to a terminal of an image forming apparatus, wherein the developer container is attachable to and detachable from the image forming apparatus and, when attached to the image forming apparatus, is electrically connected to the terminal of the image forming apparatus, the container body is provided with an identifier configured to engage with the container terminal, characterized in that the identifier is configured to change its own form that can be identified from an outside, by an external force that is applied to detach the container terminal from the container body, wherein the container body is provided with a flow preparation part that separates an inside and outside of the container body before changing the form of the identifier and allows the air to flow between the inside and outside of the container body after changing the form of the identifier, wherein the container body includes an airflow hole different from the filling port that allows the air to flow between an inside and an outside of the container body, and the airflow hole is formed by separating the identifier that engages with the container terminal, from the container body with the external force that is applied to detach the container terminal from the container body,