To provide an indoor installation capable of keeping negative ion effects generated in the life environment of human beings over a long period, and having a ground terminal to be connected to ground.

The indoor installation has the ground installed in outdoor, and a plant 1 installed in the indoor and having a layer 12 of dust coal around the root, or has a desk 6, a curtain 2, an ornament 3, a mount material 4a, 4b, 5 and the like, and at least a part contacting with the living space in the outer surfaces thereof is formed into an electroconductive face. The dust coal layer 12 around the root of the plant 1, or the electroconductive face of the desk 6, the curtain 2, the ornament 3, the mount material 4a, 4b, 5 and the like is connected to the ground installed in the outdoor by a grounding wire 7. The indoor installation has the ground terminal.