A frequency converter includes a first direct digital synthesizer that receives a signal having a predetermined frequency f_master as a clock signal and further an internal frequency setting signal, and outputs an internal signal having a frequency based on the internal frequency setting signal, and a second direct digital synthesizer that receives the internal signal as a clock signal, and further an output frequency setting signal, and outputs an output signal having a frequency f_slave (=f_master−Δ) based on the output frequency setting signal. A difference between the predetermined frequency f_master and the frequency of the internal signal is larger than a difference between the predetermined frequency f_master and the frequency f_slave of the output signal.