Plug-in unit and communication apparatus

In order to detachably mount a module to a plug-in unit while reliably realizing electromagnetic shielding of the plug-in unit in a communication apparatus having a sub-rack and the plug-in unit electrically connected to the sub-rack, the present invention provides a second shield cover member covering a portion protruding from a front end surface of a printed board in an interface part and having a first opening to expose a connection with an outside provided at a front end of the interface part to the outside, the first opening being in contact with a circumferential surface of the interface part and a shield mechanism interposed between the second shield cover member and a front cover member to cover a gap between a second opening of the front cover member and an outer circumferential surface of the second shield cover member.