A developer containing device includes: a developer container configured to contain developer and to be inserted into a receptacle defined in an image forming apparatus main body; a developer feed inlet provided in a forward end of the developer container which is inserted into the receptacle in an insertion direction and for feeding the developer contained in the developer container into the image forming apparatus main body; and an opening and closing member that opens the developer feed inlet with movement of the developer container in the insertion direction when the developer container is inserted into the receptacle and closes the developer feed inlet with movement of the developer container in opposition to the insertion direction when the developer container is removed from the receptacle, the opening and closing member having a protrusion formed to protrude inward of the opening and closing member and allowed to engage with a recess provided in the developer container and being arranged to be allowed to move on the outside of the developer container in a direction intersecting with the insertion direction of the developer container, and when the developer container is inserted into the receptacle, a developer container outside section sliding into the opening and closing member being brought to one side of the opening and closing member in the direction intersecting with the insertion direction of the developer container, then the protrusion being released from an engageable state.