A gas releasable key structure including a base, a thin-film circuit, a key cap and an elastic structure is disclosed. The elastic structure is disposed between the key cap and the thin-film circuit and includes a cap body, a ring-shaped flange, a motion pillar and a conductor. The cap body has a first opening and a second opening. The ring-shaped flange connects an edge around the first opening. The motion pillar in the cap body has a through hole, an upper surface and a lower surface. The through hole is extended to the upper surface from the lower surface, connecting the second opening. The conductor on the lower surface has an indent and a breach that connects the through hole. When the first opening is closed, the gas inside the cap body is dissipated to the exterior via the indent, the breach, the through hole and the second opening.