PROBLEM TO BE SOLVED: To provide a vegetation concrete foundation which securely retains water and keeps the retentive condition after concrete has been placed to plant a ground or a slope face with vegetation by using a water retention agent which can be effectively filled in voids of a cured body made of porous concrete. SOLUTION: A liquid water retention agent 7 fills continuous voids of a cured body 2 made of porous concrete to form a vegetation concrete foundation 1. The water retention agent 7 fills the whole cured body 2 to effectively and sufficiently retain water. Further, seeds, fertilizer, soil, etc., are also charged together therewith into the continuous voids of the cured body 2 of porous concrete. A fiber-reinforced borrow material in which seeds, fertilizer, or the like are mixed together is sprayed thin on the surface of the cured body 2 of porous concrete to grow the roots of vegetation into the voids of the cured body 2 and secure greening on a ground, a slope face, et.
