A body side unit is configured to attach a wire harness wired between a vehicle body and a slide door to the vehicle body. In the body side unit, a rotary inner is attached to the wire harness. A protector supports the rotary inner rotatably and movably in an up-down direction, and is fixed to the vehicle body. A coil spring is provided between the rotary inner and the protector, and biases the rotary inner such that the rotary inner faces downward in the up-down direction.