To provide a bag allowing an easy production of joining means of a bag inner wall and a partition when storing a vertically elongated stored object upright in the bag, and capable of two-dimensionally partitioning the space in the bag, or freely partitioning the space in the bag.

The bag includes: a housing; a central plate with I-shaped cross-section; a plurality of turning plates capable of turning about the end of the central plate; engagement means for the turning plates, such as snaps, provided at opposite ends to the turning centers of the turning plates; and engagement means for inner walls of receiving plates or the like, which are provided at the inner walls of the housing and engaged with the turning plates via the engagement means for the turning plates.