PURPOSE: To make assembly easy and eliminate pre-assembly by providing a fixing frame for fixing and holding a standing side plate in a foldable state.

CONSTITUTION: A box 15 comprises an inner box 1 and an outer box 10. Ends of a fixing frame 5 of the inner box 1 are tightly adhered by adhesive to form a parallelopipe. A bottom plate of the outer box 10 and a bottom plane 3 of the inner box 1 are tightly adhered by adhesive. The fixing frame 5 formed as a parallelopipe is folded and stored in this state until it is used. At the time of use, each side plate 2 of the inner box 1 is made to stand perpendicularly to the bottom plate 3 and upper rims 4 are folded inward. The folded fixing frame 5 is formed into a parallelopipe and fitted outside the side plates 2. A side plate 11 of the outer box 10 is made to stand, a lid plane 13 is folded to cover an upper opening of the inner box 1, and the plate 13 is fixed by a fixing jig, completing assembly. Thus the fixing frame allows the side planes to be fixed and supported, thereby making a box without adhesive at the time of use. Further since nine entire box can be snored in a flat state, a storage space can be reduced.