An telescoping antenna includes a lower antenna portion and an upper antenna portion to be telescoped into the lower antenna portion. The lower antenna portion includes a cylindrical conductor having an inner cavity for accommodating the upper antenna portion and a coaxial feeder cable. A cylindrical member, which is electrically connected to the cylindrical conductor and the coaxial feeder cable, is provided in the cavity so that a first leakage current is prevented from flowing into the coaxial feeder cable from the cylindrical conductor and that a second leakage current is prevented from flowing into the lower antenna portion from the upper antenna portion.
