To provide an independent structure for which a soundproof structure having a soundproof space sectioned by a floor part, a wall part and a ceiling part is arranged inside a sectioned space sectioned by a floor foundation, a wall foundation and a ceiling foundation constituting a building, to eliminate the propagation of sound generated from a sound source inside the soundproof space through a bridging material, and to improve a soundproof performance and a sound insulation performance.

Inside a sectioned space K sectioned by a floor foundation W1, a wall foundation W2 and a ceiling foundation W3 constituting a building W, a soundproof structure R having a soundproof space S sectioned by a floor part R1, a wall part R2 and a ceiling part R3 is arranged. A floating floor structure F for which a buffer material F1 is interposed on the floor foundation is adopted for the floor part, a wall isolation structure G which is isolated from the wall foundation with a wall gap D and has no bridging material in the wall gap is adopted for the wall part, and a ceiling isolation structure P which is isolated from the ceiling foundation with a ceiling gap T and has no bridging material in the ceiling gap is adopted for the ceiling part.