A method of inspecting defects of a transparent substrate may include: illuminating a transparent substrate; calculating an incidence angle range of light so that a first region where the light meets a first surface of the transparent substrate and a second region where light meets a second surface being opposite the first surface of the transparent substrate do not overlap each other; adjusting an incidence angle according to the incidence angle range; adjusting a position of a first detector so that a first field-of-view of the first detector covers the first region and does not cover the second region; adjusting a position of a second detector so that a second field-of-view of the second detector covers the second region and does not cover the first region; and obtaining a first image of the first region and a second image of the second region from the first and second detector, respectively.