A mobile radio unit includes two transmitting/receiving antennas (1, 2) arranged perpendicularly in a case (3), and the transmitting/receiving antennas (1, 2) are connected with a radio circuit (4) through a power distributor (5). A detector (9) is provided to detect the inclination of the case (3). A control section (10) controls impedance converter circuits (6, 7) based on the detected inclination, and changes the weight on the power distribution ratio for the antennas. An impedance matching circuit (8) adjusts the total impedance of the transmitting/receiving antennas (1, 2) and the radio circuit (4).