To decrease the radio waves plunging between two pairs of filters consisting of plural coaxial resonators placed in parallel to each other by arranging these resonators to be set opposite to each other at their short circuit end sides respectively.

The coaxial resonators of an antenna sharing device have two pairs of filters, i.e., the transmitting filters F1 and the receiving filters F2. The short circuit end faces 6 of both filters F1 and F2 are set opposite to each other with the exposed faces 8 turned down respectively. Under such conditions, the filters F1 and F2 are put on a printed board 20. At the same time, each external conductor 11 is attached to a wide conductive part 21 by soldering. A space is secured between both filters F1 and F2. Then the internal conductor 12 of the transmitting input coaxial resonator located at the outermost side of the filter F1 is set opposite to a draw-out conductor 22, and the internal conductor 12 of the receiving output coaxial resonator located at the outermost side of the filter F2 is set opposite to a draw-out conductor 23. Then the electrical capacitive coupling is secured between both conductors 22 and 23.