To provide a roof planting basement where execution property is excellent and also heat insulating property and thermo-keeping on a roof are improved.

A porous plate 10 made by porous concrete, where gaps at an upper surface side are large and those at a lower surface side are small is formed by using a large aggregate 11A at the upper surface side and a small aggregate 11B at the lower surface side and, then, a planting soil 13 is filled in the gaps of the porous plate 10. The multiple porous plates 10 are spreaded on a concrete slab on the roof of a building so as to plant vegetation in the porous plates 10.