In the first period from pumping start time T1 to time T2 in a laser light source 1, the power of pumping light L1 outputted from a pumping light source 41 so as to irradiate a laser medium 21 is at value P1 whereas the power of light L2 incident on a saturable absorber 30 after being emitted from the laser medium 21 is at an absorption saturation threshold or lower, which causes a resonator 10 to lower its Q-value, thereby suppressing the laser oscillation. Immediately before time T2, the power of light L2 is slightly lower than the absorption saturation threshold. In the second period subsequent to the first period, the power of light L2 is at value P2 greater than the above-mentioned value P1, whereas the power of light L2 exceeds the absorption saturation threshold, which causes the resonator 10 to increase its Q-value, whereby a mirror 12 outputs pulse laser light L3 to the outside.