A packing case includes a body part having a quadrangular section and a bottom part for closing a lower opening of the body part. The body part includes first to fourth side plates forming sides of the quadrangle, and first to fourth bottom plate pieces are respectively connected to lower end parts of the first to fourth side plates via fold lines. The bottom part is configured by allowing the first to fourth bottom plate pieces folded to a side of the lower opening along the fold lines to be integrally engaged with one another and to be connected with one another, and at least one support piece, which is able to assemble support body that support an object to be packed, is connected to at least one of the first to fourth bottom plate pieces.