Abstract: A box for cultivating plant such as turfs which can be mounted on the roof of the building is disclosed. Such box comprises a box body made of a bottom plate and a circumferential wall integrally connected to the periphery of the bottom plate, hollow ridges formed by elevating a part of the bottom plate, the hollow ridges having the upper surfaces thereof disposed below the upper end of the circumferential wall of the box body and a soil for cultivating plant filled in the box body, wherein the hollow ridges having water drainage apertures on the upper surface thereof and such water drainage apertures communicate with water drainage grooves defined on the rear surface of the hollow ridges. Due to such construction, the box can make the roof of the building being greenery which can be used for various purposes while protecting the surface of the roof.