PROBLEM TO BE SOLVED: To allow a radiation penetration reduction effect to be stably exhibited at a low cost.SOLUTION: A base material of the figure 1 includes a hollow plate-like member having a plurality of ribs 4, a front thin plate 2 and a rear thin plate 3 laminated via the plurality of ribs 4. Water-containing spaces 5 are formed in a region sandwiched between the front thin plate 2 and the rear thin plate 3 and excluding the plurality of ribs 4 and hollow regions of the hollow ribs 4. A water retention base material 5 is filled in the water-containing space 5. Water can be stored in the water-containing space 5 for a long period due to the water retention base material 6. Therefore, this base material can be used as a radiation shielding base material. The hollow plate-like member and each base material structure particularly exhibit a radiation penetration reduction effect, and can be manufactured at low cost. Also, a burden of transportation is reduced since water can be poured into the water-contain
