PURPOSE: To enable the growth of vegetables on the roof and the side wall of buildings such as house by natural rain, to harmonize a building with surrounding natural environment and to improve the habitation function of a building.

CONSTITUTION: A unit surface structure member 4 is fixed to a roof board 3 on a beam 2 with a nail hole 6 through its flange 5. The backing material 7 under the surface structure member 4 has a structure to store rain water 13. The upper surface material 8 contains artificial soil 15 such as sawdust, perlite or vermiculite. The soil 15 is supplied with water 13 through a water- sucking member 14. Vegetation 16 such as flower, grass and tree is grown and creeps through a window 11 to the roof to promote the carbon dioxide assimilation and enable the habitation of insects, birds, etc. The grown vegetables impart sufficiently high warmth-retaining function and heat-insulating function to the building. The building is harmonized with the natural environment, has excellent appearance and design, keeps carbon dioxide assimilating action and heat-insulating and warmth-retaining actions and enables the habitation of insects, birds, etc.