PURPOSE: To provide a box body which can be assembled and disassembled by single operation with one part.

CONSTITUTION: Flank panels 3a and 4b which are provided through hinge parts 2a and 2b to the four sides of a front panel 1 are raised and elastic engaging pieces 5 provided to an upper and a lower flank panel 4b are pressed in elastic engaged pieces 6 provided to a right and a left flank panel 3a. Then the engaging pieces 5 move onto linear projections provided to the right and left flank panels 3a and are guided to their convex surfaces to collide against the engaged pieces 6, so that they deform elastically and mutually. Then the engaging pieces 5 move beyond the engaged pieces 6, and the engaging pieces 5 and engaged pieces 6 elastically restore themselves to engage each other.