Inner cap, developer container using the same, method for closing developer container, and method for removing inner cap

摘要

An inner cap includes: an outer circumferential portion that has a part to be inserted and fit into an opening portion formed by being surrounded by a projection portion of a space portion; a slip-off preventing projection that is formed at a part located in a downstream side in an insertion direction of the outer circumferential portion to be caught by a projection portion provided on an inner wall of the space portion; an insertion stop projection that is formed at a part located in an upstream side in the insertion direction of the outer circumferential portion to be caught by the projection portion; and an insertion front end surface portion that includes a surface in a concave portion dented at a place located inwardly from the outer circumferential portion in a direction opposite to the insertion direction.