Method for realizing an inspection with short wavelength, high power light source and large numerical aperture, high performance optics to improve defect inspection sensitivity is disclosed. Short wavelength high power laser is realized by using a pulse oscillation type laser suitable for generation of high output power in a short-wavelength region. In addition, a spectral bandwidth of the laser is narrowed down so that amount of chromatic aberration of detection optics with single glass material (i.e. without compensation of chromatic aberration) is lowered to permissible level. Using highly workable glass material to construct the detection optics enables necessary surface accuracy or profile irregularity conditions to be met, even if the number of lenses is increased for large NA or the lens doesn't have a rotationally symmetrical aperture.