Discussed is a cell assembly that may include a case constituted by a first side frame and a lower frame to define an accommodation space, a battery cell accommodated in the accommodation space, a cover constituted by a second side frame and an upper frame so that the second side frame is coupled to the first side frame, the cover being installed on the case to define an installation space between a lower portion of the upper frame and an upper portion of the battery cell, and an element member disposed in the installation space and spaced from the upper frame.