The present invention relates to a high-sensitivity inspection method and apparatus adapted for the fine-structuring of patterns, wherein defect inspection sensitivity is improved using the following technologies: detection optical system is improved in resolution by filling the clearance between an objective lens 30 and a sample 1, with a liquid, and increasing effective NA (Numerical Aperture); and when a transparent interlayer-insulating film is formed on the surface of the sample, amplitude splitting at the interface between the liquid and the insulating film is suppressed for reduction in the unevenness of optical images in brightness due to interference of thin-film, by immersing the clearance between the objective lens and the sample, with a liquid of a refractive index close to that of the transparent film.