A link mechanism is provided between a first member and a second member to effect a bending/stretching motion in operative association with a telescopic expanding/contracting motion of the first member and the second member. A supporting mechanism is provided to support, to the link mechanism, a wire having flexibility and connected between a first device on the side of the first member and a second device on the side of the second member. The supporting mechanism fixes the wire to each link member of the link mechanism in position so that the wire is deformed while maintaining its state following a shape of the link mechanism in operative association with the bending/stretching motion of the link mechanism.