SURFACE DEFECT-INSPECTING DEVICE

PROBLEM TO BE SOLVED: To dynamically correct the shading of a line sensor in a detection optical system corresponding to the state of the detection part of an object to be inspected. SOLUTION: An inspection device is provided with an optical sensor 154 for generating a detection signal corresponding to a picture element, a storage means 25 for storing the level of a detection signal corresponding to a detection part by receiving a detection signal from a photosensor in a plurality of continuous points when an object to be inspected is scanned in a main scanning direction, a correction value calculation means 27 for calculating a shading correction value corresponding to a detection part based on the level of a detection signal that is obtained from the storage means, a delay circuit for delaying the detection signal by time equivalent to the scanning time of a plurality of scanning points by receiving the detection signal that is obtained from the optical sensor, and a correction means 28 for correcting the level of the detection signal being obtained from the delay circuit according to a correction value that is calculated by a correction value calculation means 27.