A plug device for plugging in at least two optical modules is provided, wherein the plug device is disposed in a housing and includes a first circuit board, a first connecting module, and a movable module. The first connecting module includes a plurality of electrical connectors, and the movable module includes a plate, at least one frame, and at least one joining member. The electrical connectors are disposed on the first circuit board. The frame is connected to the plate and has a plurality of accommodating portions. The optical modules can be respectively accommodated in the accommodating portions. The plate can be affixed to or separated from the housing by the joining member.