PROBLEM TO BE SOLVED: To speedily grow thick plant such as algae or bryophyte and continue luxuriance of vegetable for a long term, and thereby achieve a growth environment for animals and the like.SOLUTION: A method for manufacturing a concrete block includes: a first forming step of injecting normal concrete into a formwork 4 and forming it into a predetermined shape to manufacture a body part 2； and a second forming step of forming a porous layer 3 comprising porous concrete being porous on the surface of the body part 2 formed in the first forming step, thereby manufacturing the concrete block. Further, the method for manufacturing the concrete block, after forming the body part 2 comprising the normal concrete in the first forming step and in an un-hardened state of the normal concrete, supplies a porous concrete material formed by adding nutrients, which comes into contact with the surface of body part 2 in the second forming step to become the porous layer 3, thereby forming the porous layer 3 comprising the porous concrete.SELECTED DRAWING: Figure 2
