along reference lines not shown marked on the ceiling and the floor also the flat panel 400 is inserted while being brought in contact with body support members 211 a and 211 b flat panel support members 213 a and 213 b and a flat panel guide member 214 of the first main frame 210 fixed to the ceiling and the floor then a support member connecting groove 311 formed in the flat panel fixing member 310 is fastened to a support member connecting protrusion 218 formed at one end portion of the first main frame 210 such that the first main frame 210 and the flat panel fixing member 310 are fixed and the flat panel 400 is simultaneously mounted also the flat panel 400 is inserted into a flat panel insertion groove 217 defined by the first main frame 210 and the flat panel fixing member 310 to define a wall surface almost all materials formed into panels such as wood or gypsum steel and glass plates may be used as materials for the flat panel 400 a gasket 910 is inserted into a gasket insertion member 511 then the molding 510 is inserted into molding insertion grooves 212 c and 212 d which are defined by the body support members 211 a and 211 b horizontal connection frame support members 212 a and 212 b and the flat panel support members 213 a and 213 b of the first main frame 210 from both sides of the first main frame 210 so as to shield all connection portions in an upper portion of the wall structure here gasket fixing protrusions 219 and 512 and a molding fixing protrusion 912 have an effect of consolidating.