To improve stability in the plant cultivation by covering the bottom part of L-shape from the side view, with earth, and exposing an upper end part of short projecting length formed at the upper end of an erected part of this L-shape, from an earth covered face.

A block 20 is formed of a bottom part 20a and an erected part 20b into L-shape, and an upper end part 20c of short projecting length is formed at the upper part of the erected part 20b. The bottom part 20a and inner side face of this L-shape are covered with earth, and the upper end part 20c of short projecting length formed at the upper end of the erected part 20b of the L-shape is exposed from the earth covered face. The block side of the earth covered part can therefore be put in a state of being held by the bottom part 20a, the erected part 20b and the upper end part 20c of short projecting length of the block 20. The block 20 integrated with the earth covered part by this holding has no risk of falling in a right-angled direction to a connected direction. Stability in a planted state can therefore be improved.