PURPOSE: To prevent erosion of an electric wire and connector terminal due to muddy water, sea water, by a method wherein the electric wire or a connector are completely covered with a hose or a pipe, connected to a nipple, and connecting device, and connection of the air also is effected.

CONSTITUTION: A screw seat 2 is secued to a front member 1 of a hydraulic shovel, a first connecting member 3 is secured to the screw seat 2, and a second connecting member 6 is secured to the one side of the first connecting member 3 through an O-ring 8. A first nipple 9 is screwed in the other side of the first connecting member 3, and a second nipple 10 is screwed in the one end of the second connecting member 6. First and second connectors 13 and 15 are contained in a joint between the first and second connecting members 3 and 6, the first connector 13 is movable only rightward, and the second connector 15 is movable only leftward. This enables prevention of erosion of an electric wire and a connector terminal due to muddy water and sea water.