An airtight device includes a container and an airtight cover on the container, and the airtight cover includes a fixing bracket, a door, and a pressuring handle. The fixing bracket has a through hole and a guiding slot, and the through hole communicates with internal space of the container. The guiding slot has adjacent first and second top surfaces, and the second top surface is higher than the first top surface. The door selectively covers the through hole. The pressuring handle pivoted on the door has a first section, a second section, and a rotating axis between the first and second sections, and the first section rotates relative to the second section. The second section receives a force to drive the first section to move from below the second top surface to below the first top surface such that the rotating axis pressures the door.