A plant growth base (2) and a support body (14) for supporting the load of the plant growth base (2) and dividing the plant growth base (2) into a plurality of divided growth bases (2A, 2B) are provided in a greening frame (10). Vent layers (5) having vent ports (5a) opening on the reverse surface, which is on the opposite side from a plant growth surface (2a), of the divided growth bases (2A, 2B) are formed by vent layer formation boxes (4) disposed outside the greening frame (10) and attached to the greening frame (10). The vent ports (5a) of the vent layers (5) are smaller than the reverse surfaces of the divided growth bases (2A, 2B). The portions of the reverse surfaces of the divided growth bases (2A, 2B) other than the portions facing the vent ports (5a) are shielded by parts of the vent layer formation boxes (4) or separate shielding members (16).
