To provide a corner reinforcing member capable of keeping a predetermined strength even if the corner reinforcing member is of an assembling type to improve a transportation efficiency.

There are provided a first member 20 in which an incision 26 is formed at a wall 22 to extend from its end part along its axial direction and a wall 23 is formed with a rectangular cylindrical first member 20 having an incision 27 extending from its end part along its axial direction; and a rectangular cylindrical second member 30 in which a wall 32 is formed with a recess 36 extending from its end part along its axial direction and a wall 33 is formed with an incision 37 extending from its end part along its axial direction. Both members are fixed to each other while the incision 26 and the incision 36 are being inserted from each other and further they are fixed while the incision 27 and the incision 37 are being inserted from each other.