Abstract: It is an object of the present invention to accomplish a frequency synthesizer portion capable of simultaneous operations for transmission and reception with a simple configuration. A mobile communication device associated with the present invention has a frequency-switchable first VCO (11) for creating local oscillator signals for transmission and reception, respectively, and a second VCO (12) for creating a local oscillator signal for transmission in a case of simultaneous operations for transmission and reception. Furthermore, there is provided a switch (16) for connecting the first VCO (11) with a transmitter mixer (31) and a receiver mixer (21) when transmission or reception is performed and for connecting the second VCO (12) and first VCO (11) with the transmitter mixer (31) and receiver mixer (21), respectively, when transmission and reception are performed simultaneously.