To reduce the feeding line length to a lid body antenna 4 to a minimum, and suppress effectively influence of high-frequency noise generated from a signal for driving a display, in a folding-type portable telephone set where a lid body case 2 can be opened and closed to a body case 1.

In this folding-type portable telephone set, a pin terminal 6 is protruded in a lower end portion of the lid body case 2, and a socket terminal 61 is disposed at the upper end portion of the body case 1. By opening and closing operation of the lid body case 2, the pin terminal 6 is fitted in and isolated from the socket terminal 61, respectively. An opening and closing switch, constituted of the pin terminal 6 and the socket terminal 61, is interposed between an antenna feeding circuit arranged in the body case 1 and the antenna 4 disposed in the lid body case 2.