There is provided an automatic inspection apparatus and method for detecting stains on a polarizing plate using color difference analysis. The automatic inspection apparatus includes an inspection unit including at least one reference polarizing plate and a target polarizing plate or polarizing element mounted on the at least one reference polarizing plate; a light source unit disposed on one surface of the inspection unit and irradiating the inspection unit with light; an imaging unit disposed on the other surface of the inspection unit, imaging the target polarizing plate or polarizing element, and transferring an image thereof; and an arithmetic operation unit performing color difference analysis for individual inspection regions of the image of the target polarizing plate or polarizing element transferred by the imaging unit and detecting a blurred stain.