A laser light-source apparatus includes a seed light source 10, fiber amplifiers 20 and 30 and a solid state amplifier 50 configured to amplify pulse light output from the seed light source, nonlinear optical elements 60 and 70 configured to perform wavelength conversion on the pulse light output from the solid state amplifier 50 and output the resultant pulse light, a semiconductor optical amplifier 15 disposed between the seed light source 10 and the solid state amplifier 50 and configured to amplify the pulse light output from the seed light source 10, and a control unit 100 configured to execute gain switching control processing in which the seed light source 10 is driven at a desired pulse rate, and semiconductor optical amplifier control processing in which an injection current to the semiconductor optical amplifier 15 is controlled depending on the pulse rate of the seed light source 10, and thus, generation of a giant pulse can be reliably prevented, regardless of the pulse rate of the seed light source.