To provide an electric wire offering high shielding performance, which can be routed in a vehicle interior without the need for being routed under the floor of a vehicle body.

A power supply connection structure includes a shielded line including a core wire constituted by covering a conductor with an insulating covering layer, a shield layer comprising a metal braid tube covering the core wire, and a sheath made of an insulating resin covering the shield layer, and is configured, with the conductor of the core wire connected to the positive side of a power supply and the shield layer connected to the negative side thereof, such that a positive-side current path of the core wire and a negative-side current path of the shield layer are identical in axis and flow currents in parallel but opposite directions so that the magnetic field generated at the shield layer cancels the magnetic field generated at the conductor of the core wire to prevent the core wire's magnetic field from being discharged to the outside.