An ultraviolet laser-generating device, for use in a defect inspection apparatus and a method thereof, etc., comprising: a laser ray source for irradiating and emitting a basic wave of laser ray therefrom; a wavelength converter device for receiving the basic wave of laser ray emitted from the laser ray source and for converting it into an ultraviolet laser ray composed of a multiplied high harmonic light of the basic wave of laser ray; and a container having an inlet window, upon which the basic wave of laser ray emitted from the laser ray source is incident upon, and an outlet window for emitting the ultraviolet laser ray composed of the multiplied high harmonic light of the basic wave of laser ray, and installing the wavelength converter device therein, wherein the container is hermetically sealed and is filled up with an inert gas, such as nitrogen or argon gas, therein.