A pattern inspection apparatus is disclosed, which includes a first laser light source for emission of first laser light having a first wavelength, a second laser light source for emission of second laser light having a second wavelength, and a deep ultraviolet (DUV) light source for emission of DUV light with a wavelength of less than or equal to 266 nm based on the first laser light and the second laser light. A first optical fiber is provided for connecting between the first laser light source and the DUV light source. A second optical fiber is for connection between the second laser light source and the DUV light source. The apparatus also includes a pattern inspection unit with the DUV light source being built therein, for inspecting a workpiece pattern being tested by using the DUV light as illumination light therefore.