PURPOSE: To convert an antenna rod only with the removal of a cap member from an antenna housing by mounting the cap member attachably and detachably to the antenna housing and forming a lock member onto which an end stopper of an antenna rod is pressed into contact to the cap member.

CONSTITUTION: In listening to a radio set 19, when the antenna rod 15 is extended longest, the end stopper 17 is pressed into contact onto the lock part 28 to lock the antenna rod 15. The antenna rod 15 is parted from conduction springs 10, 10, but since the end stopper 17 contacts the upper end of a guide pipe 24, the radio wave received by the antenna rod 15 is delivered to the ratio set 19 without any hindrance via the end stopper 17, the guide pipe 24 and a feeder 20. If the antenna rod 15 is bent by an external force, the cap member 26 is turned and removed out of the antenna housing 23, the rest of the antenna rod 15 is parted from the antenna housing 23 together with the cap member 26.