A cardboard box dividing device and a cardboard box production device include: lower conveyors on which a plurality of connected cardboard box bodies are stacked and transported; upper conveyors disposed so as to face the lower conveyors from above and supporting upper portions of the plurality of stacked connected cardboard box bodies; a pressing device pressing, from above, the plurality of connected cardboard box bodies stacked on the lower conveyors; a cutting knife disposed along a width direction of the connected cardboard box body and dividing the plurality of connected cardboard box bodies stacked on the lower conveyors into a front part and a rear part; and a lifting/lowering device relatively moving the cutting knife and the plurality of connected cardboard box bodies on the lower conveyors along an up-down direction.