Abstract: The present invention discloses an apparatus and method for producing microcrystal particles by irradiating pulse laser beam on raw material gas and causing the raw material gas to generate dielectric gas breakdown. The apparatus includes a laser oscillator for generating the pulsed laser beam, a reactor in which the raw material gas is activated and dissociated by irradiating the pulsed laser beam, and cohered to the microcrystal particles by generating luminescence, and a control device for controlling the laser oscillator to establish a pulse spacing of the pulse laser beam larger than a duration defined as a time during which the activated and dissociated raw material gas completes cohesion and turns into the microcrystal particles in the reactor.