A UWB signal generator includes: a laser light source for generating laser light, an optical intensity modulator for modulating an intensity of laser light from the laser light source, a signal source of the optical intensity modulator for outputting a signal transmitted to the optical intensity modulator, an optical frequency shift keying (optical FSK) modulator to which output light from the optical intensity modulator is input, a signal source for controlling a signal transmitted to an RF.sub.C electrode of the optical FSK modulator, a high-frequency electric signal source for controlling a signal transmitted to an RF.sub.A electrode and an RF.sub.B electrode of the optical FSK modulator, and a high-speed photodetector for detecting an output from the optical FSK modulator.