To provide a wall panel erecting structure for a unit bathroom, which achieves waterproofing between a lower edge of a wall panel and an upper surface of a wall mounting area of a floor pan, by using a dry sealing material, and keeps the dry sealing material in a sufficiently compressed condition.

The wall mounting area 4 is formed on a peripheral edge of the floor pan 1, and an erecting piece 7 is erected from a peripheral edge of the wall mounting area 4, followed by fixing a fixture portion 17 of a retainer 11 to the erecting piece 7. Then a lower protruding piece 44 protruding from a lower edge of a surface plate 32 of the wall panel 2 to outside of the bathroom, is inserted into a gap between a retaining section 18 protruding from the fixture portion 17 to the interior of the bathroom and the wall mounting area 4, from inside the bathroom. Then the dry sealing material 49 is interposed between the lower protruding piece 44 and the wall mounting area 4, and an upper surface of the lower protruding piece 44 is press-fitted to a lower surface of the retaining section 18. Further a lower surface of the sealing material 49 is press-fitted to the upper surface of the wall mounting area 4, and an upper surface of the same is press-fitted to a lower surface of the lower protruding piece 44.