To prevent the projection of a plug when it is not used for providing a plug device with high safety by drawing the plug mounted, so as to be capable of coming out and drawing in to a housing in the housing by the energized force of a spring when the plug is pulled out of a jack.

A pushing button 12 made of a synthetic resin molding is formed, so as to be capable of sliding inside a housing 11 covered with a pressing plate 10 made of an insulating material such as a synthetic resin. One end of the pushing button 12 is faced to the opening of the pressing plate 12, and a pair of input plugs 18 is projected at the other end. The pushing button 12 is energized to the opening side by a compression coil spring 22 through a spring bracket 21, and a plug 18 is housed in the housing 11. When a plug device is connected electrically, the pushing button 12 is pushed against the energizing force of the spring 22, slid by the guide of a narrow groove 20 of the housing 11 in which a projection 19 slides, and the plug 18 is projected and inserted into a jack or a receptacle.