Cell-Case Unit and Battery Module Including the Same

A cell case unit includes a cell support member including at least one or more secondary battery cells, at least one seating portion in which the secondary battery cells are accommodated; and a case member covering the secondary battery cells accommodated in the seating portion, having a portion adjacent to both ends of the secondary battery cells to be coupled to the cell support member, and including a stretchable portion configured to be stretched in at least a portion of the case member.