To provide a knockdown box reduced in the number of components and easy in assembling work.

In the boards 1 for the knockdown box, a top board 2 (bottom board 9) and side boards 4 are integrally and successively provided and in the boundary portion of the both, a bent part 3 composed of a V-shaped groove with the cross-sectional angle of 90°, for example, is provided. A dowel 7 is mounted on an end face 2a (9a) of the top board 2 (bottom board 9) and a dowel hole 8 is formed near an end face 4a of each of the side boards 4. Two boards 1 and 1 for knockdown box are prepared, the top board 2 and the bottom board 9 are respectively bent in the bent parts 3 rectangularly to the side boards 4 and bonded by respectively inserting the dowels 7 and 7 of the top board 2 and the bottom board 9 into the dowel holes 8 and 8 on the side boards 4. At the same time, a back board 10 is fitted and attached to grooves 6 of the respective boards 1 and 1 for knockdown box so that a knockdown box K can be produced. Rack boards 11 are placed by mounting dowels on the inner surfaces of the side boards 1 and 1 as needed. Since the number of required components is reduced, production costs can be reduced, stock management is facilitated and assembly can be simplified.