Abstract: A method of producing a small expansion of laser light, in a pulse laser apparatus, including producing a small preliminary laser light by pumping a laser medium, and then, after an appropriate time lag, then pumping the preliminary laser medium at a higher intensity than the first pumping, thereby producing a laser light which is smaller in beam expansion than in the case where a preliminary pumping is not performed. The laser light which is smaller in beam expansion is due to the population inversion occurring in a small beam expansion part of pulse laser light obtained by the preliminary pumping.