Disclosed is a defect inspection device that has an illumination optical system; a detection optical system; and a processing unit which includes a defect feature quantity calculation unit that calculates the feature quantities of each defect candidate, a defect candidate grouping unit that groups the aforementioned defect candidates on the basis of the feature quantities, a defect classification evaluation value calculation unit that calculates defect classification evaluation values for the aforementioned defect candidates, a defect classification evaluation value updating unit that, on the basis of instructions, updates the evaluation values, a defect classification threshold determination unit that, on the basis of evaluation valued updated by the aforementioned defect classification evaluation value updating unit, determines a classification boundary that is a threshold for classifying defect types of the aforementioned defect candidates, and a defect detection unit that detects defects using the thresholds.