To provide an environment formation device having a more airtight through-hole through a heat insulating wall.SOLUTION: A through hole 5 is constituted by a through hole forming member 50, and sealing members 51, 52 are interposed between an inter-wall space 22 between wall members 20, 21 and the through hole forming member 50. The through hole forming member 50 has flange portions 55, 56, and seal placement portions 60, 72 are provided in opposing regions to the wall surfaces. The seal members 51, 52 have main seal portions 75, 86 and auxiliary seal portions 77, 87, where the auxiliary seal portions 77, 87 are thinner than the main seal portions 75, 86. When no external force is applied to the seal members 51, 52, the main seal portions 75, 86 project more than any part of the opposing regions to the wall surfaces in the flange portions 55, 56.SELECTED DRAWING: Figure 2
