A pulsed light generation device, includes: a first optical fiber through which first pulsed light and second pulsed light, having an intensity that decreases while an intensity of the first pulsed light increases, and increases while the intensity of the first pulsed light decreases, having been multiplexed and entered therein, are propagated; and a second optical fiber at which the first pulsed light, having exited the first optical fiber and entered therein, is amplified while being propagated therein, wherein: at the first optical fiber, phase modulation occurs in the first pulsed light due to cross phase modulation caused by the second pulsed light; and self-phase modulation occurring in the first pulsed light at the second optical fiber is diminished by the phase modulation having occurred at the first optical fiber.