The object of the present invention is to provide a modulated optical signal generator utilizing the mechanism of a multiply optical modulator, and a modulated signal generator capable of outputting millimeter waves and the like utilizing the modulated optical signal generator.The above-mentioned object is solved by a modulated optical signal generator (1) provided with an optical modulator (2), a first optical filter (3), and a second optical filter (4), wherein a frequency of a multiplying optical modulation outputted from the second optical filter (4) is controlled by controlling the frequency of the modulating signal inputted to the optical modulator (2).